如图所示，A、B为平行板电容器的金属板，G为静电计。开始时开关s闭合，静电计指针张开一定角度。为了使指针张开角度增大一 些，应该采取的措施是
A．断开开关S后，将A、B两极板靠近一些
B．断开开关S后，将A、B两极板分开一些
C．保持开关s闭合，将A、B两极板靠近一些
D．保持开关S闭合，将A、B两极板分开一些
答案：B
指针夹角与电压有关，电压越大，夹角越大，
，
断开开关，将A、B两极板靠近一些，d减小，C增大，Q不变，所以U减小。夹角变小，A错；
A、B两极板分开一些，s变小，C减小，Q不变，所以U增大。夹角变大，B对；
保持开关s闭合，电压不变，夹角不变，CD错。
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| It's no secret that many children would be healthier and happier with adoptive parents (养父母) than with the parents that nature dealt them. That's especially 1 of children who remain in homes where they're badly treated 2 the law blindly favors biological parents. It's also true of children who 3 , for years in foster (寄 养) homes because of parents who can't or won't care for them but 4 to give up custody (监护) rights. Fourteen-year-old Kimberly Mays 5 neither description, but her recent court victory could 6 children who do. Kimberly has been the object of an angry custody battle between the man who 7 her and her biological parents, with whom she has never 8 . A Florida judge decided that the teenager can 9 with the only father she's ever known and that her biological parents have "no legal right" on her. Shortly after 10 in December 1978, Kimberly Mays and another baby were mistakenly switched and sent home with the 11 parent. Kimberly's biological parents received a child who died of a heart disease in 1988. Medical tests 12 that the child wasn't their own daughter, but Kimberly was, thus leading to a custody 13 with Robert Mays. In 1989, the two families 14 that Mr. Mays would continue to have custody with the biological parents getting 15 rights. Those rights were ended when Mr. Mays decided that Kimberly was being 16 . The decision to 17 Kimberly with Mr. Mays caused heated discussion. But the judge made 18 that Kimberly did have the right to sue (起诉) on her own behalf. Thus he made it clear that she was more than just a 19 possession of her parents. Biological parentage does not mean an absolute ownership that cancels (取消) all the 20 of children. | ||||
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