常规式尾桨的构造形式主要有().
A.二叶半铰式、多叶万向接头式、多叶铰接式与无轴承式
B.跷跷板式、二叶半铰式、无轴承式
C.跷跷板式、半铰式、全铰式
参考答案:A
Peter is busy _____ at school, but he never forgets _____ exercise every day. [ ]
A. working; doing
B. working; to do
C. at work; doing
D. worked; doing
副食店原来有5桶色拉油共重75千克,又运来18桶,店里运来多少千克色拉油?