题目

根据如图所示实验，回答问题。 （1）写出实验一中铁丝燃烧的文字表达式________，硫燃烧时集气瓶底放水的目的是________；（2）实验二说明了________；（3）实验三选择了容积为40ml的试管做了测量空气中氧气的实验，(装置气密性良好)：①点燃酒精灯加热；②撤去酒精灯，待试管冷却后松开弹簧夹；③将少量白磷平装入试管中，把20mL的注射器活塞置于10mL刻度处，并按实验三图所示的连接方式固定好，再用弹簧夹夹紧橡皮管；④读取注射器活塞位置的刻请阅读下列五个人的糟糕经历，将其与上面对应的图片相匹配。其中有一项为多余选项。A.B.C.D.E.F.Yesterday was Monday.Class Eleven had a special meeting in the afternoon.The topic was about their terrible experiences last week.Here are some of them.16.Cindy：I left home at half past six.I thought I could get to school on time.However，my bike broke down halfway.I fell down and hurt my left arm.I also left my homework at home，which made my teacher very angry.I thought it was my worst day.17.Bob：We had a math test.When I finished my paper，I carelessly dropped it onto the ground.There was some dirty water，and my paper got dirty.Although I was given another clean paper，half of the test time had passed.Finally I only got a D in my math test.18.Jackson：I played volleyball with some of my classmates against the students from No.5 Middle School.Although we didn't have good players，we had teamwork.However，I fell down and hurt my right leg in the game.As a result，we lost the game.19.Helen：I hurried home with my heavy schoolbag.When I got near to the door，my schoolbag broke and dropped onto my right foot.It was so painful that I cried at once.No matter how sad I felt，nobody came to cheer me up.My parents were both out.20.David：Last night，I came back home from school and my parents weren't at home.So I decided to cook for myself.Unluckily，I was hurt by the splashing oil from the pot.Then I went to get some medicine from my neighbor.What's worse，I found I couldn't go back home because I didn't take the key.1._____2._____3._____4._____5._______