题型:填空题 已知双曲线的两条渐近线方程是y=x和y=-x,且过点D(2,3).l1,l2是过点P(-2,0)的两条互相垂直的直线,且l1,l2与双曲线各有两个交点,分别为A1,B1和A2,B2.(1)求双曲线的方程;(2)求l1斜率的范围(3)若|A1B1|=5|A2B2|,求l1的方程. 查看答案
题型:填空题 如图所示,平行板电容器与电动势为E的直流电源(内阻不计)连接,下极板接地,静电计所带电量很少,可被忽略。一带负电油滴被固定于电容器中的P点。现将平行板电容器的下极板竖直向下移动一小段距离,则:( ) A.平行板电容器的电容值将变大B.静电计指针张角变小C.带电油滴的电势能将减少D.若先将上极板与电源正极的导线断开再将下极板向下移动一段距离,则带电油滴所受电场力不变 查看答案
题型:填空题 Questions 14-23·Look at the ten statements for this part.·You will hear a short interview with George Jones, executive director for Bread for the City a private nonprofit organization.·Decide whetheryou think each statement is right(R), wrong(W) or not mentioned(NM).·Mark your answers on the Answer Sheet.The volunteers believe that their work makes a difference.A.RightB.WrongC.Not Mentioned 查看答案
题型:填空题 患者,男,60岁,突然感到心前区闷痛,伴心悸3小时,自服硝酸甘油1片,疼痛未能缓解。做心电图检查,显示如图所示:根据心电图显示,心脏病变部位是()A.前壁B.下壁C.正后壁D.前间壁E.后壁 查看答案