请帮我做一下"I'm deeply moved by ____they have done,"he said.A.when B.what C.how D.while
问题描述：
请帮我做一下"I'm deeply moved by ____they have done,"he said.A.when B.what C.how D.while
答
by是介词,介词后面就要跟宾语,显然后面就缺一个宾语从句,其次,they have done是个主谓,缺宾语,能作宾语只能是what