21.The Second World War ____ millions of people were killed ended in 1945.

　　A.when 　　 B.during that C.in which　　 D.which

　　22.Mr Crossett will never forget the days ____ he spent with his various students.

　　A.when 　 B.which C.during which D.on which

　　23.This is just the place ____ I am longing to visit these years.

　　A.that 　　 B.where C.in which　　 D.to where

　　24.It's the third time ____ late this month.

　　A.that you arrive B.when you arrived C.that you've arrived D.that you've arrived

　　25.Antarctic ____ we know very little is covered with thick ice all the year round.

　　A.which 　　 B.where C.that　　D.about which

　　26.He has lost the key to the drawer ____ the papers are kept.

　　A.where B.in which C.under which D.which

　　27.Which sentence is wrong? ____

　　A.The finger I dipped into the cup was not the one I put it into my mouth.

　　B.Do you know the boy who jumped onto the platform?

　　C.Science and new technology have made it possible for farmers to produce more food on the same amount of land.

　　D.People in ancient times took it for granted that the sun moved round the earth.

　　28.Is this museum ____ some German friends visited last Wednesday?

　　A.that 　 B.where C.in which　　 D.the one

　　29.The beautiful dress ____ Miss Jones went to the ball was borrowed from a friend of hers.

　　A.in which 　 B.worn by C.wearing which　 D.that

　　30.You may take anything useful ___ .

　　A.which you want B.you want them C.what you want D.you want