We play football ____ the field.  ( )

A．to

B．on

C．at

Jack is very busy, he _____ works ____ Sundays. ( )

A．usually; on

B．like; of

C．play; in

D．do; about

用适当的介词填空。(6分)
（1）We should be good________ animals.
（2）There are all kinds________ flowers on our planet.
（3）Mary's birthday is ________May.
（4）Pandas live  ________   the southwest  ________   China.
（5）Tom often goes to the library  ________   his friends.
（6）African elephants come________Africa.

They enjoy foods ______ bread, hamburgers and sandwiches. (    )

A．like

B．for

C．to

改变下列单词的一个字母，使其成为另外一个单词。
1. bear ________ 
2. car ________
3. say ________ 
4. snow ________
5. come ________