下列的常量中，合法的是（ ）。A．12. B．-20 C．1,000 D． 4

The death toll of the quake in New Zealand is _____ 150, but officials say the figure won’t stand because they are still getting information in．

A．exactly

B．appropriately

C．definitely

D．approximately

建设项目业主与PMC单位签订合同一般采取( )的形式。

A．成本+固定酬金

B．成本+与风险有关的奖励或罚款

C．成本+利润

D．成本+固定酬金+与风险有关的奖励或罚款

某同学一次实验中需称取5.0gNaOH用于配置一定体积一定浓度的NaOH溶液，下列操作对所配置溶液浓度无影响的是

A．所用NaOH已经潮解

B．容量瓶未干燥就使用

C．转移溶液后未洗涤

D．称量时误用“左码右物”B

After studying in a medical college for five years, Jane _____ her job as a doctor in the countryside. [ ]

A. set out

B. took over

C. took up

D. set up

输气管线上游发生爆管时，暑期场站的调压阀会（）。

A.继续运行

B.前后压差增大

C.停止运行

D.阀后压力减少