问题 单项选择题 B型题

重度二尖瓣狭窄时心电图可出现()

A.病理性Q波

B.心电图ST段普遍弓背向下型抬高

C.水冲脉

D.二尖瓣型P波

E.正弦波图形

答案

参考答案:D

解析:1.心肌梗死急性期心电图特征性改变可见深而宽的Q波(反映心肌坏死),ST段呈弓背向上明显抬高(反映心肌损伤)及T波倒置(反映心肌缺血)。 2.慢性病变导致主动脉瓣关闭不全时,收缩压升高,舒张压降低,脉压增大。外周血管征常见,包括随心脏搏动的点头征、颈动脉和桡动脉扪及水冲脉、毛细血管搏动征、股动脉枪击音等。 3.重度二尖瓣狭窄时,左心房扩大,可出现二尖瓣型P波。 4.心室扑动呈正弦波图形,波幅大而规则,频率150~300次/分。

阅读理解

阅读理解

     Don't_believe_all_of_the_stereotypes(模式化的形象)you_may_have_heard_about_Americans.Even the ones that are true in general may not be true about specific individuals or a large part of the population.For example,although Americans tend to be louder than people from other cultures(especially at athletic

events),many of the people you meet will be quiet and polite.Some people may be intolerant, but most will be pleasant and welcoming.Remember that American films and television exaggerate(夸张)in order to

generate excitement, and so present a rather false picture of what life in the United States is really like.

Therefore,tourists in the US are not always on their best behavior.

     Americans do tend to be more informal than people from other countries.It is common for Americans

to wear casual clothing to school and to greet professors by first name.However, good manners and

politeness are always appreciated.If you are polite, and dress a little more formally than your American

friends, it will not be poorly thought of.

     However,some businesses require their employees to wear a uniform or a suit.It would be improper to wear a Tshirt and blue jeans to a job interview.Some of the more prestigious restaurants require a coat and a tie.Americans tend to dress up for cultural events(the opera,theater and ballet)and to dress down for

athletic events.Formal wear is required at weddings and funerals, or any other event with religion.If you

rely on the stereotypes,you will likely put yourself into an embarrassing situation.

1. The underlined sentence probably means________.

A. some of the stereotypes you may have heard about Americans are not true

B. you should not believe the stereotypes you may have heard about Americans

C. none of the stereotypes you may have heard about Americans should be believed

D. none of the stereotypes you may have heard about Americans should not be believed

2.The passage is probably written for________.

A. businessmen  

B. visitors to America

C. American students  

D. American filmmakers

3.The second paragraph suggests that________.

A. most Americans are polite

B. people who are polite are welcome

C. casual clothing makes others uncomfortable

D. American students are impolite to their teachers

4. We can learn from the passage that________.

A. American films are mostly poor comedies

B. it is good manners to wear blue jeans to a wedding

C. Americans usually wear formal clothes in a theater

D. to dress formally makes others feel you are not easy

to get on with

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