问题
选择题
—How many on the cake?
—Three. Tom is three years old.[ ]
A. candles
B. pencils
C. apples
答案
答案：A
搜题请搜索小程序“爱下问搜题”
—How many on the cake?
—Three. Tom is three years old.[ ]
A. candles
B. pencils
C. apples
答案：A
,碰撞中无机械能损失。重力加速度为g。试求：