已知，如图，D是△ABC的BC边的中点，DE⊥AC，DF⊥AB，垂足分别是E、F，且BF=CE，求证：（1）△ABC是等腰三角形；（2）当∠A=90°时，试判断四边形AFDE是怎样的四边形，证明你的结论。

如图所示，四边形ABCD是正方形，点E是边BC的中点且∠AEF=90°，EF交正方形外角平分线CF于点F，取边AB的中点G，连接EG.（1）求证：EG=CF；（2）将△ECF绕点E逆时针旋转90°，请在图中直接画出旋转后的图形，并指出旋转后CF与EG的位置关系.

补全对话
A: Hi, Sand, what are you going to do this weekend?
B: I’m going to see a movie. Can you give me some advice?
A: Sure.1                ?
B: I like action movies.
A:Have you ever seen the movie Avatar（阿凡达）？
B：2                 .But I heard it is great.
A: Oh, I saw it yesterday.
B: 3                ?
A: I think it is the best movie I have seen.
B: 4                ?
A: It lasts about two and a half hours.
B: Is the ticket price high?
A: Yes. Watching it in 3D costs 120 yuan.
B: 5                   .
A: You’re welcome.

补全对话
A: Good afternoon, Tom. Where are you going?
B: 1             .
A: Oh, to buy books? You are out! Why not go to the Readers' Room?
B: The Readers' Room? 2                .
A: It is a place where students can exchange their old books with others.
B: That sounds great! 3               .
A: It's next to Renmin Hospital, across from City Park.
B: Oh, it's a little far. 4                .
A: You can take No. 7 bus.
B: How long does it take?
A: 5               .
B: Ten minutes isn't a long time. OK, I will go there. Thanks!

补全对话
A: Hi，David!1          ? ?
B: Hi，Sarah! I am going to see Anna. She is in hospital.?
A: 2        ?
B: She had a traffic accident on her way to school and was hurt.?
A: 3         . Is there anything serious??
B: Yes, there is something wrong with her head.?
A: Oh, my God! 4         . ?
B: I hope so, too.?
A: 5            ? ?
B: Sure. Let’s go!?

从下列句子中选择合适的句子，填到横线上
Shopkeeper: 1                .
Tim: Hello, I’m looking for a pair of football boots for my father.
Shopkeeper: Which color do you like?
Tim: I like the red ones.2                 .
Shopkeeper: They’re 150 yuan.
Tim: Oh! 3               .How about the blue ones?
Shopkeeper: 140 yuan.
Tim: Also too expensive, 4              .
Shopkeeper: Yes, the white boots cost only 100 yuan .And they’re good.
Tim: Let me see.5              .

A. Are there any cheaper ones?
B. How much do they cost?
C. They’re too expensive.
D. I will take the white ones.
E. How much is it?
F. Hello, can I help you?

从下列句子中选择合适的句子，填到横线上
W: Hello, this is Sally speaking.
M: Hello, this is Bob.
W: 1                
M: Reading a book.
W: 2                    we can watch a video.
M: OK. 3               
W: Go along Peace Street. When you get to the second traffic lights, turn left. At the end of the street, you'll see a new hotel.
M: Oh, OK. I know where that is. 4             
W: Yes. My house is across from the supermarket.
M: OK. 5                

A. How can I get to your house?
B. There's a small supermarket next to the hotel.
C. It's on the right.
D. Do you want to come over to my house?
E. What do you do?
F. What are you doing?
G. I'll see you at two thirty.

最近，上海建成了我国第一条磁悬浮铁路。磁悬浮的核心技术是利用超导体的反磁性。高温超导物质（Y₂Ba₄Cu₆O₁₃）是以Y_mO_n、BaCO₃和CuO为原料，经研磨、烧结、合成（此过程中所有元素的化合价均不变）。（1）高温超导物质（Y₂Ba₄Cu₆O₁₃）由     种元素组成，其中Y呈     价，Y_mO_n的化学式是        。（2）在合成该高温超导物质的同时，还生成了一种物质，该物质是     。（写化学式）

硅酸盐是构成地壳岩石的主要成分。化学上常用二氧化硅和氧化物的形式表示其组成。例如，镁橄榄石（Mg₂SiO₄）常以2MgO•SiO₂表示．依照上法表示下列硅酸盐的组成：高岭石Al₂(Si₂O₅)(OH)₄                 ；钙沸石Ca(Al₂Si₃O₁₀)•3H₂O                 ；滑石Mg₃Si₄O₁₀(OH)₂                 。

试依据核电荷数为1-18的元素的原子结构示意图，回答下列问题：
（1）现以第三周期（第11-18号元素）为例，仔细观察，认真思考后回答下列问题：
①从原子结构示意图分析，11～18号元素排在一行的依据：                                                       ；
②在此周期中，从左到右，原子结构变化情况：                                                       ；
③在此周期中，从左到右，元素原子得失电子的变化情况：                                                       ；
④在此周期中，从左到右，元素种类的变化情况：                                                       。
（2）上图中硫元素的核电荷数Z=    ；氯元素的最外层电子数Y=     （填数值）。
（3）核电荷数为12的元素的原子失去两个电子后，形成的粒子的符号是    。它的核外电子排布与元素    的原子核外电子排布相同（填元素符号）。