1.__b___at the town hall.the president was warmly welcomed by the mayor.

a.to arrive b.on arriving c.arrived d.have arrived
2.I wish he _c__me tomorrow.I am so busy now
will visit b.will be visiting c.visited d.would have visited
3.how careless ____john____the pretty vase.
a.it was of…to have broken
b.was of…to break
c.it was for…to have broken
d.of…to break
4.-mom,what did your doctor say?
-he advised me to live _d__the air is fresher.
a.in where b.in which c.the place where d.where
帮我解释一下这几道题，详细一点谢谢。第一题的c和d为什么不能用

1.on the radio,over the radio有何区别 1.is this the factory-----you visited the other day? 1.the experiment now comes to the( )of testing 1.they danced( )the music( )the tape recorder 1. debt is at the core of the problem. 1.The thangful mother______their children. 1.There is______popular______in the world. 1. When is the celebration? 1.The meeting was held to discuss the effects of tourism in the wildlife in the area. 1.The team leader didn't know who____(blame)for the loss of the match.