下列句子的划线处均有一处错误，请找出来。
She's
sing
under
the
tree
从所给的四个选项中选择最佳答案
______ you tell
[
A
—Bob, what are you doing there?
— ______ a book．
Zhang Hua is putting ______ her clothes.
—Are you writing it?
—No, I ______．
[ ]
A．don't B．isn't C．am not D．do
She is listening ______ the radio
A: Are they playing football?
B: Yes, they ______.
A. can B. do C. playing D. are
The man is a worker. He's ______ a bike.
A. mends B. mending C. mend D. mendding
They are ______ in the river.
A. swimming B. swiming C. swim D. swaming
----What are they doing?
----They are ______.
A. writing down the new words B. write down the new words
C. write the new words down D. writting down the new words