目前世界上绝大多数叶片都采用复合材料制造，复合材料具有哪些优点？

.(8分)某白色固体可能由氢氧化钡(化学式为Ba(OH)₂)、氢氧化钠中的一种或两种组成。为确定该固体物质的成分，某化学兴趣小组进行下列探究活动，请你认真阅读有关信息，回答相关问题。

【查阅资料】(1) Ba(OH)₂是一种强碱，具有NaOH相似的化学性质。

(2)部分酸、碱、盐的溶解性如下表所示：

【提出猜想】猜想I ：该固体是NaOH

猜想Ⅱ：该固体是Ba(OH)₂

猜想Ⅲ：该固体是Ba(OH)₂、NaOH的混合物

【设计实验】

【问题讨论】

(1)实验步骤①中发生反应的化学方程式为                                   。

(2)实验步骤②得出的实验结论                 (填“正确”或“不正确”)。

(3)如果在上述实验中用稀硫酸代替硫酸钠溶液，实验步骤和实验现象均相同，你可以判断出猜想       是成立的。

患者，女，25岁。四肢大关节游走性疼痛3年，近半年心慌气短，双下肢浮肿。检查：颈静脉怒张，双下肢凹陷性水肿，肝肋缘下3.5cm，心尖部可闻及舒张期杂音。其诊断是

A．风湿性主动脉瓣关闭不全
B．风湿性二尖瓣关闭不全
C．二尖瓣狭窄及关闭不全
D．心力衰竭
E．风湿性二尖瓣狭窄合并右心衰竭

阅读理解

     Welcome to Language upon Thames.  This brochure has been designed to give you an overview of our Language School and the courses we offer. If you have some additional questions please do not hesitate to contact us for more information.

     At Language upon Thames, we feel it is important to be flexible, in order that students can decide what period of study suits them best.

                           Small Group General English Courses

     These courses are aimed at students who wish to improve their speaking, listening, reading and writing

skills and are offered at the following levels.

     BEGINNERS

     ELEMENTARY (初级)

     PREINTERMEDIATE

     UPPERINTERMEDIATE

     Studying one of the above courses will enable you to use English more confidently and competently

on a daily basis.

     Try our free online test to see which level you are at-CLICK HERE.

                            Exam Courses

     These courses are aimed at students who wish to gain academic qualifications in English and are offered at the following levels.

     University of Cambridge exams:

     ADVANCED 1-FCE (First certificate)

     ADVANCED 2-CAE (Advanced)

     ADVANCED 3-CPE (Proficiency)

     Studying one of the above courses will enable you to continue your education or enter university in this country. (Students wishing to gain admission to a British university are normally required to have the

Cambridge Proficiency Certificate.)

                            Speaking, Listening & Pronunciation

      This course builds on communicative confidence and competence and is aimed at students who wish to develop the important skills of speaking and listening.

      Emphasis is also placed on pronunciation, with activities designed to meet the needs of students of

different nationalities, who need to focus on different areas.

      CLICK HERE to register for a General English course.

                          Other Languages

      At Language upon Thames we offer a wide range of cafeterias, restaurants, shops and bars. Most

importantly, we have foreign language classes of French, Japanese, German, Spanish and Italian during the day, evening or on a onetoone basis.

1. What does this passage mainly talk about?

A. English courses.

B. Ways to improve students' English.

C. The best way to improve your skills.

D. The importance of English.

2. If you attend Exam Courses, you will ________. 

A. use English as fluently as a native speaker

B. deal with everyday English well

C. have better pronunciation of English

D. be able to continue your education or enter university in this country

3. Judging from the description, we can tell that this passage must be taken from ________. 

A. a newspaper              

B. a magazine

C. the Internet              

D. a guidebook

4. The following statements are true EXCEPT ________. 

A. only Englishmen can attend the courses

B. the courses are designed for learners of different levels

C. one can learn French even in the evening

D. Language upon Thames is a school aimed to offer help with language learning

依据《中国南方电网有限责任公司电力安全工作规程》，在机器设备断电隔离之前或在机器转动时，禁止从靠背轮和齿轮上取下（）或其他防护设备。

A.防尘罩

B.防雨罩

C.防护罩

正畸治疗中牙根吸收多少称为明显的根吸收（）。

A.小于0.5mm

B.1～2mm

C.大于3mm

D.0.5～1mm

E.大于6mm