Tests have proved that caffeine affects the body by increasing the heart rate and rhythm, which ______ affects the circulatory system.

A．in the long run

B．in turn

C．in return

D．as a result

测定变压器的电压比应该在变压器处于（）情况下进行。

A.空载状态

B.轻载状态

C.满载状态

D.短路状态