unemployment during the past ten years.

解析：考查动词时态。句意：在过去的十年，我和很多其他中年人一样也遭遇过失业的尴尬。meet with遭遇,短暂性动作动词，一般不用在完成进行时中，这里强调动作的完成。

9.My 10-year-old son had been taking （take）apart the old clock and fixing it up again for several times before I came back home.

解析：考查动词时态。句意：我回到家之前，我10岁大的儿子已经把这个旧钟表拆卸并重新组装了好几回了。根据before从句以及and fixing it up，可知这里用过去完成进行时，强调过去某个时间前一直进行的动作。

10.My brother is an actor.He has appeared in several films so far.

解析：考查动词时态。句意：我哥哥是个演员。到目前为止他已在几部电影里出现。so far(到目前为止)通常与现在完成时连用。

Ⅱ.单句改错

1.Since I won the big prize, my telephone hasn't stopped ringing.People to ask how I am going to spend the money.

解析：考查动词时态。这里指赢大奖以来人们一直打电话询问我打算怎样花这笔钱。强调近阶段正在发生的事, 用现在进行时。

2.I won't tell the student the answer to the math problem until he been working on it for more than an hour.

解析：考查动词时态。句意：这个学生至少要在这数学题上花1个小时，我才会告诉他答案。主句为一般将来时态,until 时间状语从句需用一般现在时或现在完成时或现在完成进行时。

3.I have lived in London for many years, but I've never regretted my final decision to move back to China.

解析：考查动词时态。根据后一句判断, 我已回中国了, 因此在伦敦住了多年是过去的事了, 故用过去时态。

4.The construction of the two new railway lines has been by now.

解析：考查动词时态。从by now这个时间状语来看, 应用现在完成时；construction 与complete之间是被动关系，故用被动语态的完成时。