When we arrived at the airport, we were told our flight （）.
A. cancelled
B. had cancelled
C. has been cancelled
D. had been cancelled
下列几种浅基础类型，哪种最适宜用刚性基础假定? （）
A. 独立基础
B. 条形基础
C. 筏形基础
D. 箱形基础
稀有碱基常出现于
A. rRNA
B. tRNA
C. 冈崎片段
D. huRNA
E. mRNA
在层状岩体中开挖出边坡，坡面倾向NW45°、倾角53°。根据开挖坡面和岩层面的产状要素，下列哪个选项的岩层面最容易发生滑动破坏? （）
A. 岩层面倾向SE55°、倾角35°
B. 岩层面倾向SE15°、倾角35°
C. 岩层面倾向NW50°、倾角35°
D. 岩层面倾向NW15°、倾角35°
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