—Ten years ago.
A:when you taught in this school
B:when did you teach in this school
C:how long you taught in this school
D:how long did you teach in this school
x
π6
7π6
ωx+φ
0
π2
π
3π2
2π
Asin(ωx+φ)
2
﹣2
我国夏季气温最低的地区分布在( )
复数(1+1i)2的值是 ( )