The passage you are reading is the beginning part of a report in the original. Then, what is "This", the first word, most probably referring to

A．An offered illustration.

B．Part of a textbook on politics.

C．What the author is going to write.

D．The principle that voters are shrewder than' most politicians believe.

采用气马达启动柴油机时，气马达（）不得超过15s。

A.连续运行时间

B.断续运行时间

C.静止时间

D.高速运行时间