泵送混凝土施工中，（）情况下易发生堵管现象。
A、泵的压力异常
B、输送管道中有弯管
C、压送困难
D、输送管路震动过大
参考答案：B
--- Do you live in Beijing now?
--- ______ . It is 10 years ______ I lived here.
A．Yes; since
B．No; since
C．Yes; beofre
D．no; that
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