No more having to buy expensive textbooks which you will only use for a year or two and then sell or_______away.

__________ more and more good products, the workers kept improving their ways of production.

This country （) more obese people than underweight ones.
A.is having
B.has had
C.has
D.have

请帮忙给出正确答案和分析，谢谢！

Adult foreign learners, though having many more disadvantages than a native child, is fortunately equipped with a richer world knowledge which cannot be exploited in learning.（）

Chris Peterson was teaching a class in psychology at Virginia Tech when he told his students to fill out a carefully designed test that determines a person's level of optimism and pessimism. The students also answered questions about their general heath, including how often they went to a doctor.
Peterson followed the health of his students the following year and discovered that the pessimists had twice as many diseases and made twice as many trips to the doctor as the optimists.
Later, Martin Seligman of the University of Pennsylvania and two of his colleagues, using interviews and blood tests, found that optimists have better immune (免疫的) activity than pessimists. Why？ One big factor is that "Pessimistic individuals," as Seligman writes, "get depressed more easily and more often."
When a person is depressed, certain brain hormones (荷尔蒙) become reduced, creating a chain of biochemical (生物化学的) events that end up slowing down the activity of the immune system.
Optimists also look at information in more depth to find out what they can do about the risk factors. In a study by Lisa Aspinwall, at the University of Maryland, subjects read health-related information on cancer and other topics. She discovered that optimists spent more time than pessimists reading the severe risk material and they recommend more of it.
"These are people," says Aspinwall, "who aren't sitting around wishing things were different. They believe in a better outcome, and that whatever measures they take will help them to heal." In other words, instead of having their heads in the clouds, optimistic people look and seek. They aren't afraid to look into the situation because they're optimistic. Thus, for yet another reason, optimists are likely to be healthier.
The best news is what research has shown repeatedly: Anyone can become more optimistic with effort. And every effort you make to keep an optimistic attitude will reward you with a stronger immune system. So you'll enjoy better health.
1. The purpose of these scientific studies is to ________.
A、pick out people who are more optimistic
B、determine a person's level of optimism and pessimism
C、prove pessimistic people get depressed more easily and more often
D、discover to what degree one's health is related to one's attitude in life
2. Seligman's research suggests that ________.
A、optimism helps people become healthier
B、interviews are the main tool used in the research
C、blood tests may not produce exact results
D、one's immune system is controlled by one's thoughts
3. According to the scientists, the reduction of immune activity is basically caused by ________.
A、some uncertain factors.
B、one's worse condition of health
C、one's depressed feeling
D、the change of biochemical events
4. It can be inferred from the passage that ________.
A、optimists spend more time on studying and searching
B、pessimists are more concerned with their health
C、we can tell who is a pessimist by observing his reading behavior
D、hormones are something with mysterious effects on the brain
5. Which of the following statements is NOT true？
A、Everyone can develop an optimistic attitude with effort.
B、Pessimists have no hope of making a change in their attitude.
C、Optimists have a stronger immune system.
D、A positive attitude toward life makes us healthier.

请帮忙给出正确答案和分析，谢谢！

"Buổi sáng" 是什么意思（）

boom/buːm/（）

After having lived for over twenty years in the same district, Albert Hall was forced to move to a new neighborhood. He surprised his landlord by telling him that he was leaving because he could not afford to buy any more chocolate.
It all began a year ago when Albert Hall returned home one evening and found a large dog in front of his gate. He was very fond of animals and as he happened to have a small piece of chocolate in his pocket, he gave it to the dog. The next day, the dog was there again. It held up its paws (爪子) and received another piece of chocolate as a reward. Albert called his new friend “Bingo”. He never found out the dog's real name, nor who his owner was. However, Bingo appeared regularly every afternoon and it was quite clear that he liked chocolate more than bones. He soon grew dissatisfied with small pieces of chocolate and demanded a large bar a day. If at any time Albert couldn't give it, Bingo got very angry and refused to let him open the gate. Albert was now at Bingo's mercy and had to “buy him” to get into his own house! He spent such a large part of his week's wage to keep Bingo supplied with chocolate that in the end he had to move somewhere else.
1)、Albert had been living in the same district for all his life.
A.T
B.F
2)、Albert decided to move because he was afraid of animals, especially dogs.
A.T
B.F
3)、Bingo waited for Albert every afternoon at the gate because he liked Albert.
A.T
B.F
4)、We can tell from the story that Albert could afford to buy a large bar of chocolate for Bingo every day.
A.T
B.F
5)、Albert had to “buy him” means Albert had to give him chocolate.
A.T
B.F

电线颜色缩写中BU代表()。

根据发音规律，选出正确的单词发音 boy（）

左眼棱镜度为4△B60°也可表示为（）。

右眼改正镜为-3.00DS/-1.00DC×，90视轴在光心上方0.3cm处，该处棱镜成效为（）。