题目

A friend and I were standing in line at the grocery store the other day, and I was telling her how  41  my children were. I had come in after work that morning, and like most times, my house was broken. “I believe children nowadays are just out for what they can get. I bend over backwards for them, and they     42 even help me keep our house clean. It wouldn’t bother me so,  43  it’s the woman who looks bad if the house is in a mess.” “Do you know how  44  you are?” a woman behind us  45  . “I would love to go home and find my house in a mess. I wouldn’t min7．如图所示，在水平粗糙横杆上，有一质量为m的小圆环A，用一细线悬吊一个质量为M的球B，今用一水平力F缓慢地拉起B，A仍保持静止不动，设圆环A受到的支持力为FN，静摩擦力为f，此过程中（　　）A．FN不变，f增大B．FN减小，f减小C．FN减小，f增大D．FN增大，f减小