10、 The board deemed it urgent that these files_______ right away. A. had to be printed B. should have been printed C. must be printed D. should be printed 解析：it是形式宾语，urgent是宾语补足语，that引导的从句是真正的宾语从句，该从句的内容被认为是urgent(急迫的)，这样从句的谓语动词要求用虚拟语气形式，即should(可以省略)+动词原形。因此，本题正确答案是(D)。

9、 The board deemed it urgent that these files _______ right away. A. had to be printed　B. should have been printed C. must be printed　D. should be printed 解析： D. should be printed 。因为urgent是欲望形容词,在句中作形式宾语it的补足语,所以宾语从句中的谓语需用虚拟语气:(should)+动词原形(主动态或被动态)。

8、 I apologize if I _______ you,but I assure you it was unintentional. A. offend　B. had offended C. should have offended　D. might have offended 解析： B. had offended 。本题测试交错时间的虚拟条件句。was 暗示，事情发生在过去，所以虚拟条件句中的谓语动词应该用表示过去时间的虚拟形式。

7、 When Edison died, it was proposed that the American people _______ all power in their homes, streets, and factories for several minutes in honour of this great man. A. turn off　B. turned off　C. would turn off　D. had turned off 解析： propose是欲望动词,后接的宾语从句或主语从句中谓语要用虚拟语气：should+动词原形或直接用动词原形。选择(A). turn off

6. There is a real possibility that these animals could be frightened, _______a sudden loud noise. A. being there B. should there be C. there was D. there having been 解析：句意为：“要是有一声巨响，这些动物会受到惊吓，这是有现实可能性的。”should there be表示虚拟条件句中将来时间的谓语形式, if省略,所以should与there倒装。因此B. should there be 就是本题答案 。

5. Look at the terrible situation I am in! If only I ______ your advice . A. follow B. would follow C. had followed D. have followed 解析：题目中的第一句话表示的是现在真实的情况，而第二句话中所要表达的是应该做但事实上没有做的事，这种情况导致第一句话中真实情况的发生，故If only条件句假设的是过去一种情况，因此应该用had +过去分词，所以正确答案是(C)。

4. ______ he English examination I would have gone to the concert last Sunday . A. In spite of B. But for C. Because of D. As for 解析：假设的情况有时不是用一个条件句表示，而是隐含在一个由介词如but for、but that、without, 由连词but、副词otherwise 、比较级、形容词、独立主格等表示的上下文中。本句主句表示对过去情况的假设，但事实上由于英语考试而没有去成，即若不是因为英语考试，我本可以去听音乐会，所以应选(B)But for为正确答案。

3. If you ______ Jerry Brown until recently, you’d think the photograph on the right was strange. A. shouldn’t contact B. didn’t contact C. weren’t to contact D. hadn’t contacted 解析：until recently，因此(D)是正确答案，而主句是隐含的对现在情况的假设，该句是一个混合虚拟条件句。

2. Had Paul received six more votes in the last election, he ______ our chairman now. A. must have been B. would have been C. were D. would be 解析：这道题目是一个混合虚拟语气的句子。条件句省略了if，把助词had提前到主语前面，表示对过去情况的假设，而主句中now表明了对现在情况的假设，所以应选would(should, could, might)+动词原形这种表达形式。四个选项中只有(D)是正确表达形式，故为正确答案。

1.The millions of calculations involved, had they been done by hand, ______all practical value by the time they were finished. A. could lose B. would have lost C. might lose D. ought to have lost 解析：这个句子中含有一个省略if，把助动词提前到主语they之前的虚拟条件句，该条件句表示对过去情况的假设，而主句中by the time they were finished 表明主句也应该是对过去发生的情况的假设，因而应该选(B)would have lost为正确答案。