The astronaut did many experiments in the spaceship,            great help for knowing more about space.

A. which we think it is     B. which we think is of   

C. of which we think is     D. we think which is of

練習(xí)冊系列答案
相關(guān)習(xí)題

科目：高中英語 來源： 題型：

查看答案和解析>>

同步練習(xí)冊答案