治疗窦性心动过速的首选药（） A.美西律 B.苯妥英钠 C.维拉帕米 D.奎尼丁 E

胰体癌（）

A.左上腹痛突出，反射到腰背部，夜痛尤剧 

B.无痛性梗阻性黄疸 

C.消瘦、贫血 

D.肝和胆囊肿大压痛 

E.脐周蓝色改变（Cullen征）

The findings of a new survey have American professors talking about the good old days—when A's were a lot tougher to earn．

Sites like RateMyProfessors．com make it easy for students to find a class taught by a professor who is known as an "easy grader"．A recent survey by Kaplan Test Prep found that 46 percent of the more than 1,200 students polled admitted to using the site for just such a purpose．

"Our research shows that many of today's college students are looking at multiple factors when picking out courses: overall teacher quality that will result in a good learning experience, but also instructors who don't like to award a lot of C's and D's," said Jeff Olson, vice president of research at Kaplan Test Prep．

"While it makes sense that students would choose kinder graders, it also helps explain the recent popularity of grade inflation（膨胀）．"

Grade inflation is seen by many professors as poisoning the learning environment．Some, like former Duke University professor Stuart Rojstaczer, are righting it head-on．

On his website, Gradelnflation．com, he releases an annual list of schools where grade inflation is the worst．

This year, he decided to name the schools where grades were inflated the least．He praised, for example, Princeton University, as well as Purdue University, where the average GPA has remained around 2．8 for over 30 years．

"Purdue doesn't even seem to know that grade inflation exists in the US," Rojstaczer says．"Ignorance is bliss（极大的幸福）．"

68．From the passage we may know that Kaplan Test Prep is most probably _____

A．an institute             B．a professor 

C．a vice president        D．a course

69．Grade inflation is spreading because _____．

A．it's poisoning the learning environment

B．instructors intend to improve their overall teaching quality

C．many instructors adapt to the students' expectations

D．students get easy access to sites like RateMyProfessors．com

70．The passage suggests that _____．

A．universities will employ hard graders

B．if we want to be happy, we should be ignorant

C．A's are becoming easy to earn at most US universities

D．professors and instructors should give students higher grades

71．The writer tends to _____．

A．favor easy graders                B．see grade inflation as unavoidable

C．oppose Kaplan Test Prep         D．miss the days when A's were hard to earn

有一正弦交流电源，如下左图,电压有效值U＝120 V，频率为f＝50 Hz，向一霓虹灯供电，若霓虹灯的激发电压和熄灭电压均为U₀＝60 V，试估算在一个小时内，霓虹灯发光时间为           s．

长期衡量通常是将考察期设定在( )年(含)以上。

A．2

B．3

C．4

D．5

在规定的试验条件下，液体挥发的蒸气与空气形成的混合物，遇火源能够闪燃的液体最低温度（采用闭杯法测定），称为（）。

A.自燃点

B.闪点

C.燃点

D.着火点