下列关于图中所示的现象描述或解释正确的是（ ）
A．甲图：通过沼泽地时脚下垫木板是为了减小对地面的压力
B．乙图：起瓶器开启瓶盖时，可看作是以B为支点的省力杠杆
C．丙图：两小球相互推斥，a、b两轻质小球一定都带电
D．丁图：该装置可探究电磁铁的磁性强弱与线圈匝数的关系
答案：C
题目分析：A．甲图：通过沼泽地时脚下垫木板是增大受力面积，减小压强，A错误；
B．乙图：起瓶器开启瓶盖时，可看作是以A为支点的省力杠杆，B错误；
C．丙图：两小球相互推斥，a、b两轻质小球一定都带电，因为要排斥，必须带同种电荷，C正确；
D．丁图：该装置可探究电磁铁的磁性强弱与电流大小的关系。
故选C。
点评：关键是掌握相应的知识点，进行合理分析判断，解题不难。
Just Help the Next Person The only highway to go to work that we had to drive was closed down due to an accident on the bridge. A truck had hit the bridge and made it 36 for any traffic to go over it. So in order to get to 37 I had to go a number of miles out of my way. Not being that 38 with this road and not knowing 39 all the pot holes in the road were, I topped a hill and right in my path was a big pot hole. I felt and heard the familiar sound of a flat tire. I 40 as far to the right as possible and stopped. I tried several times to change the tire, but 41 . There I sat out in the country and no way to 42 with anybody. Just then, I looked in my rear view mirror and a 43 was pulling out of a pasture behind me. I was 44 and scared at the same time. I was struggling to get the 45 out when this man in the pickup pulled in behind me. He got out to introduce himself and 46 to help me. When he got the spare out we discovered that the spare is also 47 . He told me he would take the tire and have it 48 and call my husband. We got the tire fixed 49 he took me back to my car. My husband was there 50 us when we got back. The kind stranger stayed there and helped my husband 51 the tire. After they finished we 52 thanked him and offered to pay him for his 53 . I will never forget his words, " your thanks is 54 enough pay and I just hope if this ever happens to my wife or daughter someone will be so 55 as to help them."
|