导曲线设置超高时，其顺坡应不大于（）。
A、1‰
B、2‰
C、3‰
D、4‰
参考答案：B
--I think our school’s selective courses are of great use and I have learnt a lot from them.
--Yes _______.
A．No problem
B．I couldn’t agree with you more
C．I don’t think so
D．It doesn’t matter
