— Who came to school earliest yesterday morning?
— ______. You can ask Linda. She may know.
A:I'm afraid not
B:I think so
C:I've no idea
D:You're welcome
①蚯蚓走迷宫
②猩猩设法取高处的香蕉
③鸡绕道取食
④小学生的识字学习
如图所示,地球绕着太阳公转,而月球又绕着地球转动,他们的运动均可近似看成匀速圆周运动.如果要通过观测求得地球的质量,需要测量下列哪些量( )
读下图,完成小题。