生产矿井每延伸一个新水平，应进行（）次煤尘爆炸性实验。
A、1
B、2
C、3
D、不少于1次
参考答案：A
已知直线l：2ax+ty+3a=0（t≠0，a∈R）经过点（1，-1），求直线l的倾斜角α（结果精确到1°）
The Shanghai Expo Site covers a total area of 5.28 sq km, ______12 pavilion groups, of _____ Zone A hosts China Pavilion, and other national Pavilions for Asian countries except Southeast Asian ones.
A．included, who
B．including, which
C．included, which
D．including, what
