Question

The first thing we should do is to protect the wild...

The first thing we should do is to protect the wild animals . A．that B．which C．what D．how

Answer 1

A

修饰名词是一个句子为定语从句，若先行词是物，关系词可用which或that，但 先行词前有序数词时，通常用that，故选A。