@CharlotteDunois 指出了这一点，但是 Twig 2.0 需要 >=PHP7.0，所以在你的环境 (php 5.6) 中你不能使用 Twig 2.0.来自 Twig 官方文档:

@CharlotteDunois pointed this out, but Twig 2.0 requires >=PHP7.0, so in your environment (php 5.6) you can't use Twig 2.0. From the Twig official documentation:

先决条件

Twig 至少需要 PHP 7.0.0 才能运行.

Twig needs at least PHP 7.0.0 to run.

请注意，对于 PHP5.x 分支，您仍然可以使用 Twig 1.x

Notice that for PHP5.x branch you still have Twig 1.x aviable