A:who
B:whe
C:what
D:that
填上合适的介词。
Look ____ me.
已知等差数列{an}的前n项和为Sn,且a1=1,S3=0.
给印度带来丰沛降水的季风是( )
若3m-1有意义,则m取值范围是( )