They are doing ____useful work a.a b /说明原因，具体

What are they doing? what are they doing? what are they doing?急用! 还有一题:What.are.they.doing?They.are还有一题:What. are. they. doing?They. are the water What are they doing怎么回答 They are doing some reading.改为一般现在时 What are they doing英语作文 They are doing some very important ( ) (work) what are they doing怎么读 __________ __________ uesful work they are doing! What are they doing?--They___(play soccer) They are doing some English _(练习). They are doing homework now.改为祈使句 He watches TV______________._________ are they doing? what are they doing with it? what are they doing for vacation中文 What are they busy 后用加doing吗?（Wat are they busy doing?) They are doing----[they]homework 适当形式填空