锅炉爆管后的主要现象是（）。（A）压力急速下降 （B）排烟温度急速下降 （C）火焰发

维生素B₂（C₁₇H₂₀O₆N₄）可以用于防治舌炎、口角炎、角膜炎和溢脂性皮炎，其主要存在于牛奶、动物内脏、蛋、瘦肉、麦胚、黄豆、花生等食物中，请回答下列问题：

（1）维生素B₂由______种元素组成．

（2）维生素B₂中碳、氢、氧、氮的原子个数比为______．

（3）维生素B₂中碳、氢两种元素的质量比为______．

（4）维生素B₂中碳元素的质量分数为______（精确到0.1%）．

__________是绿色植物进行光合作用的主要器官。

阅读理解

     A common misconception (误解) -about scholarships is that they are only available for the smartest

students with the highest GPAs. However, this just isn't even close to true. There are scholarships out

there for every type of student seeking a college education. Let's take a look at each type a bit more in

depth.

     Academic Scholarships

     Academic scholarships are also often referred to as merit (优点) scholarships, though a merit

scholarship can mean anything that has some level of contest to it. These are fox; the students with the

4.0 GPAs, the years as a part of several extracurricular (课外的) activities and the well- rounded

applications. They typically have the highest payouts and are considered very well- known as they are

often national awards.

     Athletic Scholarships

     For students with strong academics (学业的) and physical skills, athletic scholarships are the way

to go. There is practically a scholarship for every single sport, from volleyball to football; gymnastics to

cheerleading. So, if you are good at anything physical, you should definitely pursue an athletic scholarship.

     Scholarships for Minorities

     There are also many scholarships for minorities available. Some of these are general and for "all

minorities as a collective whole, while others are intended for individual ethnic (种族的) groups. It is

also a good idea to apply for a minority scholarship if you are part of fully of a certain ethnicity. You

will get to represent your culture and possibly win money -- what more could you ask for?

     Scholarships for Women

     As with the scholarships for minorities above, there are also scholarships specifically for women.

Since colleges were dominated (主宰) by men for many years, scholarships have been created for

strong, career-minded women that need assistance paying for college expenses. If you are female, it is

strongly recommended you pursue a scholarship for women. Moreover, scholarships for women are

typic

ally available in just about any field. Be specific!

1. In the author's opinion, ______.

A. most people are well - informed about scholarships

B. most people think scholarships should go to the smartest students

C. most people have some misunderstanding about scholarships

D. most people deserve scholarships though not having applied for them

2. Tom does well in his lessons and is especially good at sports. The best scholarship he can

   apply for ______.

A. Academic Scholarships                 

B. Athletic Scholarships

C. Scholarships for Minorities                

D. Scholarships for Women

3. Alice is an Indian -American. She prefers to study her own culture and something about

   ethnology (民族学). Then she'd better apply for ______.

A. Academic Scholarships                  

B. Athletic Scholarships

C. Scholarships for Minorities              

D. Scholarships for Women

4. How many scholarships are intended for all tile students?

A. One.      

B. Two.      

C. Three.        

D. Four.

长期使用普萘洛尔，突然停药引起的反跳现象是

A．受体向上调节
B．受体向下调节
C．改变受体分布
D．受体耦联G蛋白加强
E．受体与G蛋白脱耦联

双侧电源的单侧回路，投检查无压一侧也同时投入检查同步继电器，两者的触点并联工作。