what‘s this 我们先看This is an eraser.这句话,对an eraser提问,就把an eraser改为what,就成了This is what?但是这是个特殊疑问句,what要提到句首,整个句子要倒装,所以是what is this? in the box是一个状语,对句子转换没什么影响,直接加在后面就可以了. 下面有人说What is,我觉得是这样的, 如果题目是An eraser is in the box.对an eraser提问,那么答案就会是what is. 你们刚学,答案会要求比较规范.