有关成人心电图正常值错误的是() A.PR间期0.12~0.20秒 B.P波时限 C

题型:单项选择题

问题:

有关成人心电图正常值错误的是()

A.PR间期0.12~0.20秒

B.P波时限<0.12秒

C.V1、V2导联J点上抬一般<0.2mV

D.QRS波群时限一般不超过0.11秒

E.QTc间期>0.44秒

考点:口腔医学(医学高级)诊断学基础诊断学基础题库
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腮腺炎的超声表现是()。

A.弥漫性增大

B.急性期呈低回声区

C.慢性期呈强回声区

D.腮腺血流信号增多

E.以上都是

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一个质量为m、电荷量为q的带电粒子,由静止开始经加速电场加速后(加速电压为U),该粒子的德布罗意波长为(    )

A.  

B.

C.

D.

题型:单项选择题

In America, drivers’ education is part of the regular high school curriculum. Every student in his or her second year of high school is required to take a class in driver’s education. However, unlike other courses, it is not given during the regular school year. Instead it is a summer course.

The course is divided up into two parts: class time for learning laws and regulations and driving time to practise driving. Class time is not unlike any other class. The students have a text from which they study the basic laws they must know to pass the written driving test that is given to anyone wanting to get a driver’s license.

Driving time is a chance for the students to get behind the wheel (steering wheel) and practice starting steering, backing up, parking, switching lanes, turning corners, and all the other maneuvers (操作) required to drive a car. Each student is required to drive a total of six hours. The students are divided up into groups of four. The students and the instructor go out driving for two hour blocks of time. Thus, each student gets half an hour driving time per outing. The instructor and “driver” sit in the front seats and the other three students sit in the back.

Drivers Ed cars are unlike other cars in which they have two sets of brakes, one on the driver’s side and one on the other side where the instructor sits. Thus, if the student driver should run into difficulties the instructor can take over. The car also has another special feature. On the top of the car is a sign that reads: STUDENT DRIVER. That lets nearby drivers know that they should use extra caution(小心) the student driver is a beginning driver, not very experienced and prone to driving slowly.

After the student has passed the driver’s education course and reached the appropriate age to drive (this age differs in every state but in most cases the person must be 16 years old), they can go to a designated state office to take their driver’s test, which is made up of an eye examination, a written test, and a road test. The person must pass all three tests in order to be given a driver’s license. If the person did well in his or her driver’s education class, he or she will pass the test with flying colors and get a driver’s license.

1. In America, the driver’s course mentioned above___________.

A. is considered as part of the advanced education

B. is given to anyone wanting to get a driver’s license

C. is carried on at the same time as other courses

D. is offered to all the students of Grade 2 in high schools

2. To prevent accidents, a drivers Ed car______________.

A. has a sign inside it                                B. has two sets of brakes

C. is big enough to hold five persons           D. can’t run very fast

3. We can infer that the students are required to ______ in their whole driving practice.

A. go out driving for twelve times                     B. spend at least six hours driving

C. drive for two hour blocks of time           D. get half an hour driving

4. Which of the following does not agree with the requirements for the students wanting to get their driver’s license? 

A. They must be 16 years of age

B. They should go to have their driver’s test

C. They must have their eyes examined

D. They ought to do well in their driver’s course

5 In the last sentence, “with flying colors” means______________.

A. happily                                                B. successfully           

C. colorfully                                                D. quickly

题型:单项选择题

在进行城市污水系统的工程设计时,常用到变化系数的概念,下列关于污水量变化系数的表述中,不正确的是()。

A.日变化系数

B.时变化系数

C.总变化系数Kx=KdKh

D.变化系数随污水量的大小而不同,污水流量越大,其变化幅度越小

题型:单项选择题

用花药离体培养出马铃薯单倍体植株,当它进行减数分裂时,观察到染色体两两配对,形成12对,据此现象可推知产生花药的马铃薯是()。

A、二倍体

B、三倍体

C、四倍体

D、六倍体

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