一个分数的分子扩大3倍，分母缩小3倍，这个分数就______倍．

—Do you think our basketballers played very well yesterday?

—_____.

A．They were not nervous at all

B．They were still young

C．They played naturally

D．They couldn’t have done better

一段均匀的镍铬合金线，将它截去一节，则剩余部分和截去前的整段合金线相比，以下物理量不变的是（　　）

A．质量

B．密度

C．体积

D．电阻

_____ your father like oranges? [ ]

A. Is

B. Do

C. Does

切盘根时，切口应整齐地砌成（）度角。

A.30

B.45

C.60

D.50

脱氢反应进料循环采样线有物料流动而开启采样阀无法放出物料则（）。

A.循环采样线未开

B.脱氢反应进料采样阀堵

C.循环采样线堵

D.水路管线堵