A _____________ friend? [ ]
A. chinese
B. Chinese
C. English
答案：B
1+2+3+4+5-96+……+30＝( )
A．475
B．465
C．455
D．445
A．mgtgθ
B．mgsinθ
C．μmg
D．μmg
mgtgθ
mgsinθ