英语专业四级必备语法 第7期(情态动词) 【卧龙雪痕整理】【南阳师范学院

外国语学院】

七、【情态动词】

相关用法

请主要注意情态动词完成式的用法有两方面的含义：

1.表示已经发生的情况

(1)must have +过去分词，表示对已发生情况的肯定推测，译为“(昨天)一定 ”。如： My pain must have been apparent the moment I walked into the room, for the first man I met asked sympathetically: “Are you feeling all right?”

(2)can’t/couldn’t have +过去分词，表示对已发生情况的否定推测，译为“(昨天)一定没 ”。 如：

Mary couldn’t have received my letter; otherwise she would have replied before now.

(3)may/might have +过去分词，表示对已发生的事情做不肯定、可能性很小的推测，或事实上根本没发生，译为“也许 ”。如：At Florida Power’s Crystal River plant, a potentially serious leakage of radioactive water may have been unknowingly caused by an electrician.

2.表示虚拟语气

(1)needn’t have+过去分词，表示做了不必做的事，译为“其实没必要 ”。如： As it turned out to be a small house party, we needn’t have dressed up so formally.

(2)should /should not have +过去分词，表示应该做某事但实际上未做，或本不应该做但实际上做了, 译为“本(不)应该 ”。如：I regret having left the work unfinished; I should have planned everything ahead carefully.

(3)ought to have+过去分词，表示动作按理该发生了，但实际上未发生，译为“该 ”，与should的完成式含义类似。如：

The porter ought to have called the fire-brigade as soon as he saw the fire in the stock, which went up in smoke.

(4)could have+过去分词，表示过去本来可以做但却未做，译为“完全可以 ”。如： What you said is right, but you could have phrased it more tactfully.