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$(1)$尝试探究:如图$1$,$\triangle ABC$是等边三角形,$\angle DAB=90^{\circ}$,$AD=AB$,连接$CD$、$BD$,求$\angle CDB$的度数. $(2)$类比延伸:如图$2$,$\triangle ABC$是等边三角形,$AD=AB$,连接$CD$、$BD$,$AE$平分$\angle DAC$,交$BD$于$E$,交$CD$于$F$,求$\angle CDB$的度数. $(3)$

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数学课上,老师让同学们利用三角形纸片进行操作活动,探究有关线段之间的关系. 问题情境: 如图$1$,三角形纸片$ABC$中,$\angle ACB=90^{\circ}$,$AC=BC$.将点$C$放在直线$l$上,点$A$,$B$位于直线$l$的同侧,过点$A$作$AD\bot l$于点$D$. 初步探究: $(1)$在图$1$的直线$l$上取点$E$,使$BE=BC$,得到图$2$,猜想线段$CE$与$AD$的数量关系,并说明理由；

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A．用方框中所给单词的适当形式填空。每词限用一次。 enter begin heart possible crazy (1) At the _________of this year, I made a wish that I would make progress in math. (2) I am ________about collecting stamps. I think they are amazing beyond wor

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1.Too much homework; Don’t have enough time for their hobbies. Advice:Make a plan for study and hobbies. Find time to relax as possible as you can. 2.Too much tiring homework; Bad reading and writing habits Advice: Do ho

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(C) A “Gap Year” is a period of time when a student takes a break* before going to university. It is often spent travelling or working. More and more American students are preparing for college by taking a gap year. The

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o travel around the world is the dream of many adventurous* people. But very few people can afford to travel all over the world because hotels, food and airplane tickets are too expensive. Some people, however, have thou

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Let’s Explore (探究) The Nature Are you interested in animals and nature? Want to enjoy your summer holiday and learn something interesting and useful?Here comes your CHANCE！ Youth Explore has prepared you with a THREE DAY

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I’m really willing* to tell every person what I experienced on a snowy night. That night, I sat with my friend in a well-known (1) . As we talked and enjoyed ourselves, a man entered and sat down beside us . He called th

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All the people think______impossible for Wang Wu to win the first prize .

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Eating an apple a day makes me ______.

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As a little boy, Jimmy is ______young______ look after himself.

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In fact, this pair of trousers ____ her 200 dollars.

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--Miss Smith is not in her office.She has gone to Britain. --When ____she _____there?

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Li Mei has been in America ______3 years, and she misses her family very much.

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The supermarket sells a lot of things, _______food, clothes and toys.

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Would you mind if I open the window? The air here______so bad.

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Lily is ____active girl and she is interested in playing _____guitar.

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已知,如图长方形$ABCD$中,$AB=3cm$,$AD=9cm$,将此长方形折叠,使点$B$与点$D$重合,折痕为$EF$,则$\triangle ABE$的面积为（ ）

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如图,$\triangle ABC$是等边三角形,$F$、$G$分别为$AC$和$BC$的中点,$D$在线段$BG$上,连接$DF$.以$DF$为边作等边$\triangle DFE$,$ED$的延长线交$AB$于$H$,连接$EC$,则以下结论:①$BF\bot AC$；②$\angle AHD+\angle AFD=180^{\circ}$；③$\angle BCE=60^{\circ}$；④当$D$在线段$BG$上（不与$G$点重

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已知在等腰$\triangle ABC$中,$AB=AC$,$BC=m.\angle BAC=30^{\circ}$,点$D$是直线$BC$上一点,连接$AD$,在$AD$的右侧作等腰$\triangle ADE$,其中$AD=AE$,$\angle EAD=30^{\circ}$,连接$CE$,则$(AE+\frac{\sqrt{3}}{3}CE)$的最小值为______(用含$m$的代数式表示).

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