运输货车的制造标准是：当汽车侧立在倾角为30°的斜坡上时，如图1-4（原图1-17）所示，仍不致于翻倒，也就是说，货车受的重力的作用线仍落在货车的支持面（以车轮为顶点构成的平面范围）以内．如果车轮间的距离为2.0m，车身的重心离支持面不超过多少？（设车的重心在如图所示的中轴线上）

An (71) service bus (ESB) acts as a shared messaging layer for connecting applications and other services throughout an enterprise computing infrastructure. It supplements its core (72) messaging backbone with intelligent tansformation and routing to ensure that messages are passed (73) . Services participate in the ESB using either Web Services messaging standards (74) the Java Message Service. ESBs are increasingly seen by users and analysts as core components in (75) IT.

（73）处填（）。

A．relying

B．rely

C．reliably

D．reliable