可用作各级公路的基层的是( )。
A．石灰稳定土基层
B．水泥稳定土基层
C．填隙碎石基层
D．级配砾石基层
E．石灰工业废渣稳定土基层、
参考答案：B,D
—Is Miss Gao at school?
—_________, I don't know.[ ]
A. Excuse me
B. Yes
C. Sorry
D. No
—Do you think the weather will be all right this summer?
—No, _____ we are lucky. The newspaper says it'll be very hot anyway.
A．if
B．though
C．unless
D．as
