Complete each sentence with a suitable preposition and whom or which
1.The keys ____ _____ he opeans the doors have been lost.
2.A change ____ ____ no new substance is formed is a physical change.
3.There stand some chairs ,two ____ ____ are well shaped.
4.The persons ____ ____ I have been working are honest.
5.September 10 is Teacher's Day ,____ ____ teachers usually hold a celebration.
6.She has written another book on engineering, the name ____ ____ I have forgotten.
7.The patient ____ Dr.Black operated ____ to weeks ago has recovered.
8.This telephone has a small screen _____ _____the speakers are able to see each other.
9.The company has more than 30 offices,all ____ ____ are connected to a single computer.
10.Rose, ____ ____ I went to the concert ,enjoyed it very much.