题干

对下列情景涉及的物理知识,描述正确的是(    )

A:在冰雪路面上行车,需加装防滑链是为了增大与地面的摩擦

B:课本静止放在水平桌面上,课本对桌面的压力与桌面对它的支持力是一对平衡力

C:向墙上按图钉时,手对图钉帽产生的压强等于图钉尖对墙壁产生的压强

D:宇航员登上月球时,他的质量比在地球上时的质量减少了

上一题 下一题 0.0难度 选择题 更新时间:2017-02-16 08:50:36

答案(点此获取答案解析)

A

同类题1


 Molly Boylan is one of the most successful business women in Canada after setting up her cosmetic (化妆品) company Blazes in 1992. Though she is very successful, she says that she finds it harder every year in balance (平衡) her business with her family life. She sometimes feels that her two children know more about their baby---sitter than they do about her.

 Molly employs (雇佣) around eighty people in her factory and warehouse, and ten others in her two new fashion stores, but her newest employee is the most important one for her. After years of worrying about her business more than her family, she has decided to make Sally Pamonte new general manager in her company. Molly will still be involved in decision- making, and she's going to stay in touch with the people who work for her, but Sally is going to look after day-to-day running of the business so that Molly can spend more time with the kids.

 The new arrangement (安排) is going to start on Monday, and both of them are already excited about it. Sally says, "I'm very nervous, actually, but I'm sure Molly will help me a lot in the early days, even though I hope she feels she can trust me not to make too many mistakes.”

 Molly, on the other hand, seems quite relaxed about the whole thing. ”I know that Sally's going to be a very nice manager.”she says, "She's only been here a couple of days and she's already shown me how to work out a few problems we were having. The best thing though is that I feel a hundred times happier than I've been in years. I mean, I honestly can't remember the last time I felt as relaxed as this, and my kids are really excited about my being at home more. To be honest, I wish I had made this decision years ago.”