Problem when installing laravel 5.4

php
laravel

#1

When I trying to create a laravel project, the error shown.
I has already upgrade php to 7.1

$ composer create-project --prefer-dist laravel/laravel myproject 5.4
Installing laravel/laravel (v5.4.0)
  - Installing laravel/laravel (v5.4.0) Loading from cache
Created project in myproject
> php -r "file_exists('.env') || copy('.env.example', '.env');"
Loading composer repositories with package information
Updating dependencies (including require-dev)
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - phpunit/phpunit 5.7.9 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.7.8 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.7.7 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.7.6 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.7.5 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.7.4 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.7.3 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.7.21 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.7.20 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.7.2 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.7.19 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.7.18 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.7.17 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.7.16 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.7.15 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.7.14 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.7.13 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.7.12 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.7.11 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.7.10 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.7.1 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.7.0 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.6.8 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.6.7 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.6.6 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.6.5 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.6.4 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.6.3 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.6.2 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.6.1 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.6.0 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.5.7 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.5.6 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.5.5 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.5.4 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.5.3 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.5.2 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.5.1 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.5.0 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.4.8 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.4.7 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.4.6 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.4.5 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.4.4 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.4.3 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.4.2 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.4.1 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.4.0 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.3.5 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.3.4 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.3.3 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.3.2 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.3.1 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.3.0 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.2.9 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.2.8 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.2.7 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.2.6 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.2.5 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.2.4 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.2.3 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.2.2 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.2.12 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.2.11 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.2.10 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.2.1 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.2.0 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.1.7 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.1.6 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.1.5 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.1.4 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.1.3 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.1.2 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.1.1 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.1.0 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.0.9 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.0.8 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.0.7 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.0.6 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.0.5 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.0.4 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.0.3 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.0.2 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.0.10 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.0.1 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/phpunit 5.0.0 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - Installation request for phpunit/phpunit ~5.0 -> satisfiable by phpunit/phpunit[5.0.0, 5.0.1, 5.0.10, 5.0.2, 5.0.3, 5.0.4, 5.0.5, 5.0.6, 5.0.7, 5.0.8, 5.0.9, 5.1.0, 5.1.1, 5.1.2, 5.1.3, 5.1.4, 5.1.5, 5.1.6, 5.1.7, 5.2.0, 5.2.1, 5.2.10, 5.2.11, 5.2.12, 5.2.2, 5.2.3, 5.2.4, 5.2.5, 5.2.6, 5.2.7, 5.2.8, 5.2.9, 5.3.0, 5.3.1, 5.3.2, 5.3.3, 5.3.4, 5.3.5, 5.4.0, 5.4.1, 5.4.2, 5.4.3, 5.4.4, 5.4.5, 5.4.6, 5.4.7, 5.4.8, 5.5.0, 5.5.1, 5.5.2, 5.5.3, 5.5.4, 5.5.5, 5.5.6, 5.5.7, 5.6.0, 5.6.1, 5.6.2, 5.6.3, 5.6.4, 5.6.5, 5.6.6, 5.6.7, 5.6.8, 5.7.0, 5.7.1, 5.7.10, 5.7.11, 5.7.12, 5.7.13, 5.7.14, 5.7.15, 5.7.16, 5.7.17, 5.7.18, 5.7.19, 5.7.2, 5.7.20, 5.7.21, 5.7.3, 5.7.4, 5.7.5, 5.7.6, 5.7.7, 5.7.8, 5.7.9].

  To enable extensions, verify that they are enabled in your .ini files:
    - /etc/php/7.1/cli/php.ini
    - /etc/php/7.1/cli/conf.d/10-opcache.ini
    - /etc/php/7.1/cli/conf.d/10-pdo.ini
    - /etc/php/7.1/cli/conf.d/20-calendar.ini
    - /etc/php/7.1/cli/conf.d/20-ctype.ini
    - /etc/php/7.1/cli/conf.d/20-exif.ini
    - /etc/php/7.1/cli/conf.d/20-fileinfo.ini
    - /etc/php/7.1/cli/conf.d/20-ftp.ini
    - /etc/php/7.1/cli/conf.d/20-gettext.ini
    - /etc/php/7.1/cli/conf.d/20-iconv.ini
    - /etc/php/7.1/cli/conf.d/20-json.ini
    - /etc/php/7.1/cli/conf.d/20-mbstring.ini
    - /etc/php/7.1/cli/conf.d/20-mcrypt.ini
    - /etc/php/7.1/cli/conf.d/20-phar.ini
    - /etc/php/7.1/cli/conf.d/20-posix.ini
    - /etc/php/7.1/cli/conf.d/20-readline.ini
    - /etc/php/7.1/cli/conf.d/20-shmop.ini
    - /etc/php/7.1/cli/conf.d/20-sockets.ini
    - /etc/php/7.1/cli/conf.d/20-sysvmsg.ini
    - /etc/php/7.1/cli/conf.d/20-sysvsem.ini
    - /etc/php/7.1/cli/conf.d/20-sysvshm.ini
    - /etc/php/7.1/cli/conf.d/20-tokenizer.ini
  You can also run `php --ini` inside terminal to see which files are used by PHP in CLI mode.
momowonghk:~/workspace (master) $ php --ini
Configuration File (php.ini) Path: /etc/php/7.1/cli
Loaded Configuration File:         (none)
Scan for additional .ini files in: /etc/php/7.1/cli/conf.d
Additional .ini files parsed:      /etc/php/7.1/cli/conf.d/10-opcache.ini,
/etc/php/7.1/cli/conf.d/10-pdo.ini,
/etc/php/7.1/cli/conf.d/20-calendar.ini,
/etc/php/7.1/cli/conf.d/20-ctype.ini,
/etc/php/7.1/cli/conf.d/20-exif.ini,
/etc/php/7.1/cli/conf.d/20-fileinfo.ini,
/etc/php/7.1/cli/conf.d/20-ftp.ini,
/etc/php/7.1/cli/conf.d/20-gettext.ini,
/etc/php/7.1/cli/conf.d/20-iconv.ini,
/etc/php/7.1/cli/conf.d/20-json.ini,
/etc/php/7.1/cli/conf.d/20-mbstring.ini,
/etc/php/7.1/cli/conf.d/20-mcrypt.ini,
/etc/php/7.1/cli/conf.d/20-phar.ini,
/etc/php/7.1/cli/conf.d/20-posix.ini,
/etc/php/7.1/cli/conf.d/20-readline.ini,
/etc/php/7.1/cli/conf.d/20-shmop.ini,
/etc/php/7.1/cli/conf.d/20-sockets.ini,
/etc/php/7.1/cli/conf.d/20-sysvmsg.ini,
/etc/php/7.1/cli/conf.d/20-sysvsem.ini,
/etc/php/7.1/cli/conf.d/20-sysvshm.ini,
/etc/php/7.1/cli/conf.d/20-tokenizer.ini