问题
选择题
—Mr. Wang's never been to Canada, has he?
—_______. He went there on business last week. [ ]
A. No, he hasn't
B. Yes, he has
C. No, he has
D. Yes, he hasn't
答案
答案：B
搜题请搜索小程序“爱下问搜题”
—Mr. Wang's never been to Canada, has he?
—_______. He went there on business last week. [ ]
A. No, he hasn't
B. Yes, he has
C. No, he has
D. Yes, he hasn't
答案：B
一质量m = 1．0kg的小滑块（可看成是质点）。当圆盘转动的角速度达到某一数值时，滑块从圆盘边缘滑落，滑块与圆盘间的动摩擦因数μ = 0．2，圆盘所水平面离水平地面的高度h = 2．5m，g取10m/s2．