根据汉语意思完成下列译文。

1.  他们准备在武汉建一座地铁.

They are going to _____ a _____ in Wuhan.

2.  我打算退休后去一个美丽而宁静的地方.

I'm going to _______ ________ quiet and beautiful.

3. 两名运动员同时到达终点.

Two runners got to the finishing line _______ the ______ time.

4. 我确信他昨天生病了.

I _____ ______ that he was ill yesterday.

5. 我打算搞一次画展,为自己存一些钱.

I'm going to _______ an exhibition and ______ some money for myself.

试论述规模收益变动规律及其原因。