The keys:

　　一、1. Are ,flying,I am 　2. Are sitting,　3.Is,talking　 4. are plying 　5. are,doing　 6.am singing 　7. is,mending 　8. is mending 　9.are plying　10.is cooking

　　二、1.C　 2.B 　3.C 　4.A 　5.A 　6.B　 7.C　 8.D  9.D  10.B

　　1、working  singing  playing  studying  having  dancing  writing  taking  running  sitting  shopping  swimming  lying

　　2、The boy isn't playing basketball.  Is the boy playing the basketball ?  Yes,he is./No,he isn't,

　　What's the boy doing?  Who's playing basketball?

　　They aren't singing in the classroom. Are they singing in the classroom? Yes,they are/No,they aren't. What're they doing? Where're they singing?

　　4、are doing singing is mending is mending Are flying I am Is sitting Are asking are playing doing am eating is working is putting Is cleaning is playing is running is singing is singing

　　5、CDCAB BBCAB CB