题目

如图甲是小明做测定“小灯泡的电功率”的实验的电路，已知小灯泡的额定电压为2.5V，小灯泡的电阻约为10Ω，滑动变阻器上标有“20Ω  1A”字样。请帮小明完成该实验：（1）如图甲所示，小明在连接电路时，还有两条导线未连接，请在图中用笔画线代替导线把电路连接好（不要更改原有导线，且导线不允许交叉）。（2）闭合开关前，小明应将滑动变阻器的滑片置于______端 (选填“A”或“B”) 。（3）小明连接好电路后，闭合开关，移动滑片，发现小A group of swans flew down to a beach where a crow was jumping around. The crow watched them with disdain. “You have no flying skills at all!” he said to the swans. “All you can do is to move your wings. Can you turn over in the air? No, that’s beyond you. Let’s have a flying competition. I’ll show you what real flying is!” One of the swans, a strong young male, took up the challenge. The crow flew up and began to show his skills. He flew in circles, performed other flying tricks, and then came down and looked proudly at the swan. Now it was the swan’s turn. He flew up, and began flying over the sea. The crow flew after him, making all kinds of comments about his flying. They flew on and on till they couldn’t see the land and there was nothing but water on all sides. The crow was making fewer and fewer comments. He was now so exhausted that he found it hard to stay in the air, and had to struggle to keep himself from falling into the water. The swan pretended not to notice, and said, “Why do you keep touching the water, brother? Is that another trick? “ “No,” said the crow. He knew he had lost the competition. “I’m in trouble because of my pride! If you don’t help me, I’ll lose my life...” The swan took pity on him, and took him on his shoulders and flew back to the beach. (   ) 46. The crow met the swan on a ___________ A. beach      B. field      C. lake    D. ground (   ) 47. What’s the correct order of the following events? a. The crow followed the swan and got into trouble. b. The swan felt pity for the crow and saved it. c. The crow had to ask the swan for help. d. The swan accepted a challenge of performing flying tricks. A. a, d, b, c    B. a, b, d, c    C. d, a, c, b      D. d, c, a, b (   ) 48. What does the underlined word “took pity on” in the last paragraph mean? A. 对…… 怜悯    B. 对……后悔   C. 对……蔑视   D. 对……失望 (   ) 49. The underlined sentence means ____________ . A. The swan began to fly.        B. It is the turn for the swan to feel proud. C. The crow began to fly.        D. It is the turn for the crow to feel proud. (   ) 50. What do we learn from the passage? A. Practice makes perfect.       B. The early bird catches the worm. C. No pains, no gains.          D. Pride goes before a fall.