A:唐长安
B:元大都
C:明北京
D:清京师
⑴ ____
⑵ ____
⑶ ____
⑷ ____
⑸ ____
A. playing football B. laughing C. crying D. standing E. singing a song
如图所示,一小滑块从光滑的1/4圆弧的最高点由静止滑下,滑出槽口时速度方向为水平,槽口与一个半球顶点相切,若要使小物块滑出槽口后不沿半球面下滑,则R1、R2应满足的关系是( )
找出下列句子正确的答语。
A. No, there aren't.
B. Yes, it is.
C. Yes, I like it very much.
D. No, I can't.
E. Yes, there is.