由于此钻机钻孔直径较小，故爆破后产生的煤岩块度（）。
A.较大
B.较小
C.等同
参考答案：B
— I’m really glad to see you back.. ______ your trip to the valley interesting?
— No. it ______ very heavily there the whole time.
A．Was; was raining
B．Is; had rained
C．Was; was to rain
D．Is; has been raining
正数的反码与原码______。
