问题
选择题
25. ―Look! What a mistake! Why?
―Sorry, I _________ on it.
A．don’t concentrate
B．hadn’t concentrated
C．haven’t been concentrating
D．wasn’t concentrating
答案
答案：D
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25. ―Look! What a mistake! Why?
―Sorry, I _________ on it.
A．don’t concentrate
B．hadn’t concentrated
C．haven’t been concentrating
D．wasn’t concentrating
答案：D