题目

如图所示，长方体形的物块a静止在水平地面上，长方体形的物块b叠放在物体a上。现对物体a施加一个水平向左的恒定拉力F，但a、b仍然都处于静止状态。以下说法正确的是（） A . a受b向右的摩擦力 B . b受a向左的摩擦力 C . 仅减小a、b接触面间的动摩擦因数，a与b可能会发生相对滑动 D . 若将F改为斜向上对物体b施加，大小不变，有可能ab一起向左运动根据所给提示，完成句子。每空一词，含缩略词。小题1:There was a football match on TV last night.(变为一般疑问句）_______  __________  a football match on TV last night ?小题2:He’s been in China since ten years ago.(变为否定句）He  ________  _________ in China since ten years ago.小题3:Tom got up early in order to catch the first bus to Chongqing.(同义句）Tom got up early ______  _______  he could catch the first bus to Chongqing.小题4:Steve will finish his book in a month. (对划线部分提问）_______  _________ will Steve finish his book?小题5:邮件英语是一种为了节约时间而正在被使用的书面语。（完成句子)E-mail English is a kind of _______   English which is being used to  ______  time.