题目

如图，在△ABC中，∠ B=90°，AB=6cm，BC=8cm，点P从点A出发沿AB边向点B以1cm/秒的速度移动，点Q从点B出发沿BC边向点C以2cm/秒的速度移动.【小题1】如果P、Q分别从A、B同时出发,经过多长时间,使△PBQ的面积为8cm2？【小题2】如果P、Q分别从A、B同时出发, 当P、Q两点运动几秒时，有最小值，并求这个最小值. 答案：p;【答案】【小题1】如图,设经过x秒后使得使△PBQ的面积为8cm2.则PB的长度为(6-x)cm,BQ的长度为2xcm,根据题意,可列方程:  解之得经过2秒,点P到离B点4cm处,点Q到离B点4cm处;经过4秒,点P到离B点2cm处,点Q到离B点8cm处,即经过2秒或者4秒, 使△PBQ的面积为8cm2.【小题2】设经过y秒, .则PB的长度为(6-y)cm,BQ的长度为2ycm,根A friend wrote me a letter a few weeks ago. He felt ___________ at the time. He ___________ his letter with this question: "We can't really change this crazy world we live in, can we? "I _________ to him and started my own letter with these words: "Yes, we most certainly can!" I can still remember someone who changed my world. She was the _________ teacher at my primary school. I liked her music class and I wanted to impress(给…留下印象) her. ___________, I didn't know how to play any instruments.One day, she let me try playing her guitar. I did my best, but could only stumble along(断断续 续地弹奏). When I finished playing, I put my _________ down. "I guess I am not very good." I told her. She looked at me with her _________ eyes, smiled at me and said, "We are all good at something. You just need to find out _________ you are good at. Then, you can share it with the world."___________ simple words changed me. They __________ a seed(种子) in my heart that continues to grow to this day. They made me realize that I had something good inside of me. I just had to find it and share it.Can you change the world? Yes, you can! You can change it through one choice, one person or one kind act at a time. ____________ you have to do is to share your goodness. Mother Teresa once said, "God doesn't ask us to do ____________ things, but small things with great love." So make your love great!1.A. glad B. homeless C. hopeful D. hopeless2.A. posted B. ended C. added D. continued3.A. replied B. answered C. said D. phoned4.A. math B. Chinese C. English D. music5.A. But B. Luckily C. However D. Especially6.A. head B. hand C. face D. fingers7.A. tired B. kind C. sad D. quiet8.A. that B. whose C. what D. why9.A. This B. That C. His D. Those10.A. harvested B. fed C. planted D. watered11.A. Both B. All C. Nothing D. Either12.A. great B. small C. good D. bad 1.D 2.B 3.A 4.D 5.C 6.A 7.B 8.C 9.D 10.C 11.B 12.A 【解析】 作者的朋友来信告知他自己的失落和不顺，然后作者通过自己的经历告诉朋友，我们每个人都可以通过自己的闪光点来改变这个世界，让这个世界变得更美好。 1.句意：那时他感到很绝望。A. glad高兴的；B. hom...