在洪涝灾害地区,人们常用两种物质处理河水,一种是明矾,用于吸附水中悬浮杂质使其沉

题型:问答题

问题:

在洪涝灾害地区,人们常用两种物质处理河水,一种是明矾,用于吸附水中悬浮杂质使其沉降,另一种是漂白粉,用于杀菌消毒.漂白粉的主要成分是CaCl2与Ca(ClO)2,它是由化工厂用氯气与熟石灰作原料制得的,假如现有主要成分占80%的漂白粉63.5g.请计算:(化学方程式为2Cl2+2Ca(OH)2=CaCl2+Ca(ClO)2+2H2O.)

(1)漂白粉中主要成分的质量为多少?

(2)欲制得63.5g这种漂白粉,需氯气的质量为多少?

考点:化学反应方程式的计算
题型:问答题

汽轮机凝汽器真空变化将引起凝汽器端差变化,当真空升高时,端差()。

A、不变;

B、增大;

C、减小。

题型:问答题

Drinking a lot of water does not do any good to the body, according to two experts in the United States. In fact, they warn, drinking too much water could be, in certain Cases, harmful.

In a study, Dr Stanly Goldfarb and Dr Dan Negoianu, both of the Renal, Electrolyte and Hypertension Division at the University of Pennsylvania, the United States, have denied the popular belief that drinking a lot of water clears body toxins (毒素) better, improves skin, and helps reduce weight.

Dr Goldfarb and Dr Negoianu say that they found little proof to support the public opinion that drinking 8 glasses of water every day benefits health. At the same time, they found little proof of harm in drinking 8 glasses of water every day.

It is widely believed that in some cases — such as athletes, people who live in hot, dry  environments, and those with certain medical conditions — drinking a lot of water indeed helps,  but no studies have been done to prove the benefits of this practice in average, healthy people, the  website medheadlines. com reports.

The study at the University of Pennsylvania also examined reports that some people experienced increased headaches when their consumption of water was low. In one small study, which the doctors reviewed, the group drinking the most water reported fewer headaches than the control group, “but the difference in the number of headaches was so small between the two groups as to be considered unimportant.”

The researchers concluded that there is no scientific proof to support that average, healthy people need to drink at least 8 glasses of water each day.

The website medheadlines. com says that, according to an Indian doctor, drinking too much water is harmful. If water enters the body more quickly than it can be removed, problems can occur.

1. What’s the key message delivered in the passage?

A. Drinking too much water might bring harm.

B. Whether to drink enough water makes no difference.

C. Drinking too much water may cause headaches.

D. Average, healthy people should drink more water.

2. We can learn from the passage that 8 glasses of water every day ________.

A. proves good for the body             B. has scientific proof of harm

C. is sure to reduce headaches            D. is generally considered necessary

3. Who may agree that drinking lots of water helps to lose weight?

A. Two experts.                     B. General public.

C. An Indian doctor.                  D. A website.

4. According to the passage, we know that ________.

A. the website medheadlines. com is developed by an Indian doctor

B. the study was carried out by two experts with an Indian doctor

C. the two experts performed the study at the University of Pennsylvania

D. drinking 8 glasses of water every day can cure certain diseases

题型:问答题

白肋烟干燥设备网带速度是通过调整网带主传动减速机的()来调整运行速度的。

A、减速比

B、调速手柄

C、变频器频率

D、传动链轮大小

题型:问答题

权变模型由谁提出的()。

A.葛西亚

B.马斯洛

C.泰勒

D.费德勒

题型:问答题

《论语》说“君子不器”,即是讲一个成熟、大写的君子人格也必定是一种自由而不甘为器皿、为工具的独立人格。

更多题库