Sincethereisabundantfoodinthesea,itisunderstandablethat...

問題詳情：

Since there is abundant food in the sea, it is understandable that some of the creatures that   evolved on land __________ to the sea.

A. would have returned              B. could have returned

C. might have returned              D. should have returned

【回答】

D

知識點：虛擬語氣與情態動詞

題型：選擇題