安慰诱导物(gratuitous inducer)
参考答案：能诱导酶的合成，但不被分解的分子，称为安慰诱导物。
--- Can I see the headmaster at the moment, please ?
--- I’m afraid not. He _______out. He _____in 10 minutes.
A．goes; comes
B．gone; came
C．will go; will come
D．has gone; will come back
水泵的比转数在一定程度上反映了（）的几何形状。
A、泵壳
B、泵轴
C、叶轮
D、填料函
