开机前，（）必须检查采煤机调高千斤顶销轴及挡板是否齐全。
A.采煤司机
B.采面班长
C.机电维护
D.采面组长或群监员
参考答案：A
(2013·天津高考)If he had spent more time practising speaking English before, he ________ able to speak it much better now.
A．will be
B．would be
C．has been
D．would have been
从柑桔中炼制出有机物（如图），下列有关它的推测不正确的是（ ）
A．分子式为C10H16
B．常温下为液态，难溶于水
C．它属于芳香烃
D．1mol该物质与1molHCl加成所得产物有四种
