when→while

　　3．He realized that his house must have been broken into the minute he got home and saw that everything was in a mess.

　　minute→moment

　　4．He was looking for the dictionary whenever he thought he might have put it.

　　whenever→wherever

　　5．No matter if he is free he must go to the library.

　　if→whether

　　6．I have not missed a play or a concert when I was seventeen years old.

　　when→since

　　7．Next time that I plan to travel in London I'm going to take a plane.

　　that去掉或改为when

　　8．I'm not going to talk on the point any further though it is neither important nor very interesting.

　　though→because

　　9．Much since I like all the books I can't afford to buy them.

　　since→as

　　10．Alice was waiting for the bus then she noticed a thief running out of a shop.

　　then→when

　　Ⅳ.语法填空

There are many taxi drivers in our city. They often like to chat with passengers __1__ (kill) time when the taxis are caught in traffic jams. The other day I went home by taxi.__2__ (know) I was a student the driver told me that he was once a student twenty years ago.__3__ (fortunate) his family could not afford the school fees so he dropped out of school at __4__early age. He encouraged me to work hard and go to a good college. I __5__ (move) by his kindness but what really impressed me next was his honesty. __6__ arriving home I soon realized that I had left my cell phone in the taxi. Greatly __7__ (worry) I immediately called my number praying the driver would answer. Then came the driver's voice from the other end. He told me he had been expecting my call and that he would __8__ (glad)return my phone where he droped