問題詳情
9. Five coronal mass ejections have been released from the sun in a short period of time, _______ due to hit the Earth and cause geomagnetic storms.
(A) three of them
(B) three of which are
(C) three of them are
(D) three are
參考答案
答案：B
統計：A:3,B:9,C:2,D:0,E:0
難度：計算中