让步状语从句比较状语从句时间状语从句引导词 在复合句中担任状语成分的从句称为状语从句。按其意义可分为时间，地点，原因，条件，让步，结果，目的，方式，比较状语从句等。状语从句可放在主句的前后，一般用逗号隔开。状语从句常由引导词（连接词）引导。 让步状语从句 连接词though, although，后面的从句不能有but，但是 though 和yet可连用。 Although it's raining, they are still working in the field.  虽然在下雨，但他们仍在地里干活。 比较状语从句 引导词及用法：（not） so / as … as,  than,  the +比较级… the +比较级…, except/excepting that...（除了...）如： He is a good man except/excepting that he is fond of drinking.  他是个好人，除了/除了他喜欢喝酒。 新概念英语视频 八年级上册英语书人教版 人教版初二英语知识点 时间状语从句 连接词：when/while/as,till/until,since,before/after, once /as soon as/the moment/the minute/the instant/immediately/ directly/instantly, /no sooner…than /hardly（scarcely,rarely）…when ,the first（second…）last/next/every /each /by the time等 when/while/as 都表示“当...的时候”，但when侧重某一时刻的动作或状态，while侧重某一持续时间段的动作或状态，as侧重紧接着发生的动作或状态，强调“同一时间，一先一后，一边...一边”。 I will discuss it with you when I meet you again. 我会和你讨论，当我再次遇见你。 when的其他用法及意义： （1）“突然，正在此时”，常构成以下结构： be（was/were）+ doing sth/about to do sth/on the point of doing sth/to do sth/on one’s way to...+when（vted）... /had done…+when（vted）.. I was walking along the street when suddenly someone patted me on the shoulder from behind. 我正在街上走着，突然有人从后面拍了拍我的肩膀。 （2）“既然/如果” I wonder why he has posted me many packages when（=now that）he works with me together. 我不知道他为什么和我一起工作时给我发了许多包裹。 At 10：35 am.on Dece mber 17,1903，two brothers from Ohio flew the first successful airplane for 12 seconds and 120 feet along a beach in Kitty Hawk，North CarolinA．With Orville flying first，the brothers took turns as pilot，and they flew three more tim es that day.On their fourth try，they managed to go 852 feet in 59 seconds—an amazing feat at the time.The two brothers had invented powered flight. Orville and Wilbur Wright owned a bicycle shop in Dayton，Ohio.Although they had not gone to school to learn about airplanes or engineering，they were good mechanics.By repairing bicycles，they had learned how gears and pulleys worked.They also learned to take careful notes about what they saw.Each time they made a new design and tested a machine，they took notes and made drawings.They would study these to figure out what they could do better the next time. Before the Wright brothers flew，they did many things to prepare for this extraordinary achievem ent.They read everything they could find about air，balloons，a nd kites.Then they made careful sketches of what they wanted to build.They began by making model kites to learn how air flowed over wings.They made them bigger and bigger until they had a glider — a kite that is big enough t o hold a person，but with no engine.The Wright brothers made three gliders before building their first airplane.Each time they made a glider，they would test it，make careful observations，and then improve their design. When they made a glider that flew well，they added an engine.This step was harder than it sounds，because they had to find an engine that was both light­weight and powerful.The engines that they could buy were either too heavy or too weak，so they asked their friend Charlie Taylor to help them build one.The first engine that Charlie built broke almost immediately，but the second one worked well. After Orville and Wilbur installed the engine in their plane，they were almost ready.They simply had to wait for the perfect day with just the fight amount of wind.On the morning of December 17,1903，they had their chance.And the airplane flew into history. 1．What was the speed of the first flight? A．10 feet per second.  B．120 feet per minute. C．12 feet per second.  D．1200 feet per hour. 2．What can we learn about the Wright brothers from paragraph 2? A．They had little formal education. B．They owned a successful business. C．They were very thorough in their work. D．They had experienced many failures. 3．The brothers constructed a number of kites in order to_____________________. A．test the materials they would use for their plane B．prove that building a flying machine was possible C．see which shape could support the most weight D．improve the design of their plane's wings