Php 无法在Ubuntu 14.04中通过命令行安装Composer？

我无法在Ubuntu 14.04上安装Composer，原因是：

sudo curl-sS | php

我得到一个错误：

#!/usr/bin/env php
Some settings on your machine make Composer unable to work properly.
Make sure that you fix the issues listed below and run this script again:

The json extension is missing.
Install it or recompile php without --disable-json

The openssl extension is missing, which means that secure HTTPS transfers are impossible.
If possible you should enable it or recompile php with --with-openssl

当前PHP版本：

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下面列出的

问题的哪一部分您不明白？我明白，但我仍然无法安装它。你能帮我吗？你的系统是如何安装PHP的？妈妈？自制的？yum？你最初是如何安装PHP的？你以前有没有得到过？因为json（至少）应该由defaultsudo apt get install php5 json安装
PHP 5.5.3 (cli) (built: Feb  9 2015 12:47:41) 
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