Can you tell me the        difference between the words “require” and “request” ? I sometimes get puzzled by their meanings.

A．arbitrary

B．clumsy

C．apparent

D．tentative

某车难起动，检测发现水温传感器信号正常，系统油压正常，点火高压与能量正常，应该（）

A.检查喷油器

B.更换油泵

C.更换点火线圈

D.更换水温传感器