We've got food for as many people as want it.

as want it这里是少了什么成分吗？有点理解不了。如果是定语从句多了个it也不对。

【答】as...as...结构，第二个 as 暗示着做了从句的某个成分，这个成分就是“含有比较项”的那个词语。比较项是 many，而 many 修饰people，所以，as 表示“people”。这样，从句就不缺成分了。

Things are not always as they appear.

as前面是找了什么成分吗？

【答】比较从句as they appear， 作表语。

The boy has made as much progress as we had expected. 

等于：we had expected much progress？定语从句的as是代词吧？

The boy has nade as much progress as possible.

这个as是连词吧？

【答】as 后省略了成分，不必分析。记住、会用即可。