请详细说明为什么不选其他的,谢谢
来源:百度知道 编辑:UC知道 时间:2024/05/29 18:51:26
The greek philosopher made what ___ the first known study of sea life.
A believed to have been
B is believed to have been
C believed to be
D is believed to be
请详细说明为什么不选其他的选项,谢谢
A believed to have been
B is believed to have been
C believed to be
D is believed to be
请详细说明为什么不选其他的选项,谢谢
又是你啊……这种题要多给点分……
B
首先一定有 is
因为what is ... 整体是宾语从句,what 后面一定要有动词。
所以 A C不选
D:由于be发生在believe之前,所以用to have been
选B
因为表示过去,而且是被动,只有这个合适。