【问】 It is essential that he____efficient.
 A. can be B. will be C. be D. could be(TOEFL，70.1)
 主语从句中的谓语动词be是否应改为is?
 【答】 英语里有些形容词在意义上与情态或意愿有关，如essential(重要的，不可少的)，im-portant(重要的)，necessary(必须)，imperative((非常必要的)，vital(生命攸关的)，impossible(不可能的)，obligatory(必须)，appropriate(适当的)，advisable(明智的)，desirable(好的，所希望的)，preferable(更好的)等等。当用先行词it充当主语而用它们充当表语时，则that从句的谓语动词或者用现在时虚拟式(在美国英语里)，或者用should+动词原形(在英国英语里)：
 1. It is essential that the meeting be postponed. (TOEFL)
 会议有必要延期。
 2. It's imperativ e that you should not be seen here. (LDCE)
 你必须马上离开这里。
 3. It is vital that Mr Jones should receive this letter before this evening. (JED)
 重要的是琼斯先生在今晚以前要收到这封信。
 4. It is vital that we arrive at the hospital soon. (Chambers)
 刻不容缓的是我们要尽早赶到医院。
 5. It is necessary，absolutely，that I should return it this morning. (Bennet)我绝对必须在今早把它还回去。
 6. It is necessary that I get the text of my revision typed.(Yeats)
 我必须把复习用的课文打印好。
 7. It's advisable that everyone should have a map. (PEG)
 最好每个人手里都有一张地图。
 8. It is most desirable that he should attend the conference. (ALD)
 最大的希望是他能来参加会议。
 9. It is appropriate that this tax be abolished. (CGEL)
 废止这条税收是适宜的。
 10. It is imperative that they arrive on time for the lecture. (TOEFL)
 他们必须准时来听课。
 11. It is vital that we move quickly. (TOEFL)
 我们必须迅速离开。
 请做下面的试题：
 1. It is________ that the meeting be closed.
 A. important B. good C. useful D. nice(TOEFL 教程)
 2. It is________ that the meeting be closed.
 A. nice B. useful C. right D. imperative(TOEFL 教程)
 3. It is necessary she here twice a to help the room. (EPT)