問題詳情

20 Many UFO sightings can’t _____easily because most of the time people don’t know exactly whatthey have seen.
(A) explain
(B) have explained
(C) be explained
(D) have been explained

參考答案

答案：C
難度：適中0.666667
統計：A(0),B(2),C(4),D(0),E(0)