1.Do you know our town at all?
No, this is the first time I ___ here.
A. was B. have been C. came D. am coming
解析：答案B. This is the first time 后面所加从句应为现在完成时，故选B。
2.Have you ____ been to our town before?
No, it's the first time I ___ here.
A. even, come B. even, have come C. ever, come D. ever, have come
解析：答案D. ever意为曾经或无论何时，反意词为never，此两词常用于完成时。 This is the largest fish I have ever seen. It is / was the first time +that-clause 的句型中，从句要用完成时。 注意：非延续性动词的否定形式可以与表示延续时间的状语连用。即动作不发生的状态是可以持续的。
3.The students ___ busily when Miss Brown went to get a book she ___ in the office.
A. had written, left B，were writing, has left C. had written, had left D. were writing, had left
解析：答案D. "把书忘在办公室"发生在"去取书"这一过去的动作之前，因此"忘了书"这一动作发生在过去的过去，用过去完成时。句中when表示的是时间的一点，表示在"同学们正忙"这一背景下，when所引导的动作发生。因此 前一句应用过去进行时。
4.He had no sooner bought the car than he sold it.
He said he________me a present unless I_______ in doing the experiment.
A.had not given; had not succeeded B. would not give; succeed C. will not give; succeed D. would not give; will succeed.
解析：答案B. 在时间，条件或让步主语从句中一般不用将来时。本题有He said，故为过去式。主句用将来时，故选B. 此处用一般过去式代替了过去将来时。