根据材料内容，选择正确答案。

Dear Frank,    

    Thank you for your postcard. I'm very glad you are having a good trip now. Ottawa is very beautiful in May. I hope I will have a chance to go there one day.

    Our summer holidays will start next month. I enjoy my summer holidays, although(虽然)it's hot at that time in America. During summer holidays，I can swim in the sea and go fishing. It's so cool. And I am going to our hometown near Chicago with my sister Linda，and my parents agree(同意). Our uncle lives  there，so Linda and I can stay with him.

    We are not going to take a plane. We are going there by train. I am going to fish there. And Linda likes painting. She is going to do some painting there. I'm sure we'll have a good time.

                                                            Sincerely,

                                                              Jack

 按照题目要求作图：
(1)如图所示的钢丝钳，其中A是剪钢丝处，B为手的用力点，O为转动轴（支点），右图为单侧钳柄及相连部分示意图．请在图中画出钢丝钳剪钢丝时的动力臂L₁和阻力F₂．

(2)通过图示滑轮组向上提升重物，请画出最省力的绕绳方法．

(3)使电路中各用电器正常工作，在O中填入适当的电表符号，使每个用电器均能工作，并标出正负接线柱．