m,n互为相反数,则3-m-n=( )。
3
Can you give me to eat ?
A.something good enough
B.something enough good
C.enough good something
D.enough something good
核磁共振氢谱中,化学位移值的范围是()
A.51~60
B.41~50
C.31~40
D.21~30
E.0~20