单项选择题：风湿病常见的联合瓣膜损害是A．主动脉瓣和肺动脉瓣 B．二尖瓣和三尖瓣 C．二尖瓣和主

题型：单项选择题

(14分)．酸碱中和滴定是中学化学常见实验。

Ⅰ右图表示50mL酸式滴定管中液面的位置，如果液面处的读数是a，则滴定管中剩余液体的体积是______mL

　A、a　　　 B、大于a　　 C、小于(50-a)　　 D、大于(50-a)

Ⅱ　某同学欲测定某浓硫酸样品的物质的量浓度，进行了以下实验操作：

　A．冷却至室温后，在100mL容量瓶中定容配成100mL稀硫酸。

　B．量取20.00mL稀硫酸于锥形瓶中并滴入几滴指示剂。

　C．将酸式滴定管和碱式滴定管用蒸馏水洗涤干净，并用各待盛溶液润洗。

　D．将物质的量浓度为1.50mol·L^－1标准NaOH溶液装入碱式滴定管，调节液面记下读数V₁。

　E．继续滴定至终点，记下读数为V₂。

　F．在锥形瓶下垫一张白纸，把锥形瓶移到碱式滴定管下小心滴入NaOH标准溶液，边滴边摇动锥形瓶。

　G．量取浓硫酸样品5mL，在烧杯中用蒸馏水溶解。

　H．重复以上实验。

请回答下列问题：

（1）该实验正确操作步骤的顺序为　　　 → A→　　　　 →　　　　 →D→　　　　 →　　　　 → H（用编号字母填写）。

（2）量取5mL浓硫酸的仪器是　　　　　；量取20.00mL稀硫酸的仪器是　　　　　　　　。

（3）选用的指示剂是　　　　　　　。滴定过程中，视线应注视　　　　　　　　；判断到达滴定终点的现象是　　　　　　　　　　　　　　　　　。

（4）下表是实验测得的有关数据：

查看答案

完形填空。
My name is Tom. I'm thirteen years old. I'm __1__ England. My parents and I are in China now. They want to study (学习) __2__ . I live in Shanghai __3__ my father and my mother. I have got a __4__ but no sisters. My grandparents aren't with us.__5__ are in London with my brother. Shanghai is a big city. There are __6__ people here. Now I __7__ at a middle school. I am a new student, but I have got two good __8__ . They are Daming and Lingling. After school, we often watch television and play football. We __9__ play computer games. My father and mother are __10__ . They teach English in our school. We all love our school and the city.
( ) 1. A. to ( ) 2. A. English ( ) 3. A. and ( ) 4. A. grandfather ( ) 5. A. They ( ) 6. A. some ( ) 7. A. teach ( ) 8. A. friends ( ) 9. A. very ( ) 10. A. doctors	B. at B. French B. with B. uncle B. We B. many B. live B. teachers B. too B. workers	C. from C. Chinese C. or C. daughter C. You C. any C. study C. children C. also C. teachers	D. of D. Japanese D. but D. brother D. He D. much D. drive D. brothers D. well D. students