问题描述：
选择正确的be动词填空is,am,are
1,he----working quietly
2,you----sitting on the chair
3,falling behind -----annpying
4,i-----having a good day
5what-----they doing?
1,he----working quietly
2,you----sitting on the chair
3,falling behind -----annpying
4,i-----having a good day
5what-----they doing?
问题解答：
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