题目

When a giraffe has ______ drink, it has to stand with its front legs wide apart in order to reach ______ water easily． A．不填；不填                         B．a; the  C．the; 不填                         D．不填；the 答案：B摩托车上的热机工作时提供动力的是A.吸气冲程 B.压缩冲程 C.做功冲程 D.排气冲程