SUCH AS 地用法

180. Researchers have questioned the use of costly and experimental diagnostic tests to identify food allergies, such as milk, that supposedly disrupt normal behavior.

A. to identify food allergies, such as

B. to identify food allergies, like

C. to identify food allergies, such as to

D. for identifying food allergies, like that of

E. for identifying food allergies, such as for

这是XDF补充材料中的第180题，答案是C,为什么这里要加一个to?such as 和like的区别在哪里？或者说，such as 地用法是什么？

谢谢各位NN门的解答了。

If the to is omitted, the sentence would sound as if milk was one of the fool allergies.

Like and such as are exchangeable when they mean "for example". For instance,

Some sports, such as base jumping, can be really dangerous.

本题的考点是: 1)固定搭配the use of sth to do sth；2)such as与like的区别

such as 可以表示举例，such as A1, A2... ; such +n +as A1, A2...;

例如：Cartoon characters such as Mickey Mouse and Snoopy are still popular.

      Such cartoon characters as Mickey Mouse and Snoopy are still popular.

like 不能表示举例。