问题
单项选择题
An old lady was living next door. I heard her（）as I passed her room last night.
A.is coughing
B.coughing
C.to be coughing
D.to coug
答案
参考答案：B
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An old lady was living next door. I heard her（）as I passed her room last night.
A.is coughing
B.coughing
C.to be coughing
D.to coug
参考答案：B