侦查人员对所扣押的涉及国家秘密的证据，应当严格保密。( )

冷冻系统排放不凝气的目的是（），降低功耗。

— I borrowed 10 dollars from Cathy, but she insisted that I had borrowed 15 dollars from her.

— I _____ you the money. Why didn't you ask me? [ ]

A. must lend

B. could have lent

C. would lend

D. should have lent

热焊灰铸铁可以有效地防止产生（）

A.过热和裂纹

B.白口和裂纹

C.白口和碳化

D.增碳和裂纹

选择电源时，主要考虑哪几个方面（）。

A、电源的输出特性；

B、电源的体积；

C、电源的经济性；

D、电源的适应性。