山体的高度一般应高出平地乔木的浓密树冠线，约在（）cm之间。
A10-40
B10-30
C15-40
D1-10
参考答案：B
The teacher together with the students _____discussing Reading Skills that ______newly published in America.
A．are; were
B．is; were
C．are; was
D．is; was
出现制动失效后，要首先控制方向，再设法控制车速。
