若单项式-5x3ym的次数是9，则m=______．
由题意，得3+m=9，
解得m=6．
故答案为6．
This project _____ considered thoroughly, and I’m sure it _____ finished on time.
A．must be; may be
B．should be; can be
C．may be; must be
D．can be; should
GPWS的下降率过大警告（方式1）与（）.
A.仅与襟翼位置有关
B.与起落架位置无关
C.襟翼和起落架位置无关
D.襟翼和起落架位置有关
