例句: That small country at one time (A) must be (B) prosperous, for (C) it enjoyed a high level (D) of civilization. (答案:B must have been, 表示对过去的肯定推测) In a (A) way I agree with you, but I think (B) you could present (C) your arguement in a much better (D) way. (答案:C could have presented, 表示"本来可以…"但实际没有做的虚拟意义) I regret having left (A) the work unfinished (B) .I should plan (C) everything ahead (D) carefully. (答案:C should have planned, 表示"本应该做"而实际未做的虚拟意义) A piece of evidence shows (A) that life may exist (B) on earth (C) 3?8 billion years ago (D) . (答案:B may have existed, 表示根据逻辑推理对过去事情作出的可能性推测) I got up early (A) but I didn′t need to do (B) so, because (C) I had no work to do (D) that morning. (答案:B needn′t have done, 表示做了不必做的事) He knew (A) that she mustn′t have taken (B) the book as (C) she hadn′t been (D) in the house at that time. (答案:B couldn′t have taken, 表示对过去的否定推测)
6.ought to have 过去分词, 表示动作按理该发生了, 译为"该…"。 来源:考试大 7.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…"。
注意下面几个情态动词的习惯用法: had better do…(没有不定式符号to) had better not do…(not的位置不在had后面) would like to do…(带to) would not like to do…(注意not的位置) used to do…(to后接动词原形, 不是 ing形式)