—"_______ are these tomatoes?"—"Five yua

--- I paid him 300 yuan for the sneakers．

--- Oh, he charged you too much．You _____ them with half the money．

A．could have bought

B．needn’t have bought

C．must have bought

D．wouldn’t have bought

You are well prepared for the job interview, ______ there’s no need for you to get so nervous.

A．or

B．while

C．but

D．so

HPLC（）

A.气相色谱法

B.高效液相色谱法

C.十八烷基硅烷键合硅胶

D.红外分光光度法

E.差示扫描量热法

急性短暂性精神障碍的共同特点主要有( )。

A．以精神病性症状为主

B．在两周内急性起病

C．在1～3个月内可完全恢复

D．起病前有相应的心因

TD-SCANNER分析仪不具备一下那个功能（）

A.GPS定位和同步

B.频谱扫描分析

C.单音信号（CW）测量

D.天线下倾角测量