对前往我国台湾地区投资的项目和前往未建交国家投资的项目，不分限额，由 ( )核准或经国家发展和改革委员会审核后报国务院核准。

A．国务院
B．商务部
C．国家发展和改革委员会
D．国务院对外贸易主管部门

One disadvantage of using regular dry chemical (sodium bicarbonate) in firefighting is that（）.

A.it can break down under high heat and emit noxious fumes

B.it will decompose under prolonged storage and lose its effectiveness

C.fire has been known to flash back over the surface of an oil fire

D.it is ineffective in fighting fires in high-voltage electrical equipment