用逐点计算法求牵引构件各点上的张力,起点()进行。
A.必须为相遇点
B.必须为分离点
C.必须为最小张力点
D.可是任意点开始
参考答案:D
English teaching in China didn't enter into the formal educational system until the ______ century.
A. late 19th B. early 20thC. mid-20th D. late 20th
采用水泥捻口连接的管道,捻口完毕后用湿泥或草袋封口养护不小于()。
A、48h
B、36h
C、24h
D、12h