A:That
B:What
C:Whether
D:Where
如图所示,一箱苹果沿着倾角为θ的斜面,以速度v匀速下滑.在箱子的中央有一个质量为m的苹果,它受到周围苹果对它的作用力的方向( )
Helen ____ (study) English, Chinese. Maths, Science and Art at school.
Funtawild Adventure is very popular and _____________ tourists visit it year by year.