Sometimes, you might not finish drinking your glass of water before you go to bed. You might want to drink it the next morning. But have you ever wondered if it is still safe to drink?

“If you have clean water in a clean glass, you’re fine to drink it for a day or two,” Kellogg Schwab from the Johns Hopkins University Water Institute in the US told Time.

But you may find that it tastes strange. That’s because after about 12 hours, the carbon dioxide in the air reacts with the water in your glass, slightly lowering its pH level.

Also, there might be more microorganisms in your water if you leave it out overnight. Microorganisms grow more quickly at room temperature. These microorganisms can stick to your glass. They can make you get sick more easily. But as long as you clean your glasses very often, this will not be a problem.

In countries like the US and UK, people often drink water directly from the tap . This is OK – however, tap water cannot be stored for a long time. Most experts say that tap water has a shelf life of six months, according to Zane Satterfield from West Virginia University, US. After six months, there is less chlorine in the water and bacteria start to grow. You’d better not drink the water otherwise you may get sick.

What about plastic water bottles? Schwab said people should be careful with them. If you leave a bottle of water under the sun or in a car for a long period of time, the plastic produces a chemical called BPA. This chemical can cause heart disease and cancer.

1.According to the passage,the water in the glass tastes strange after about_______.

A. 12 hours B. 2 hours

C. a day and a night D. two days

2.Why does the water taste strange after a night?

A. Because there is less chlorine in the water.

B. Because the glasses are dirty after a night.

C. Because the plastic produces a chemical called BPA

D. Because the carbon dioxide in the air reacts with the water , lowering its pH level.

3.The underlined word “ microorganisms” in the fourth paragraph probable mean “________”

A. 漂浮物 B. 微生物 C. 抗生素 D. 废弃物

4.Which of the following is not true?

A. You may get sick more easily after you drink the water overnight.

B. It’s not a right way to leave a bottle of water under the sun for a long time.

C. Many people drink water directly from the tap because of no bacteria in the running water.

D. Kellogg Schwab advised us to drink clean water in a clean glass for a day or two.

When David was young, he often provided the old people in this mountain village with whatever they wanted as soon as possible.

At that time, he noticed that many old people had much difficulty in buying what they needed, especially after heavy snow. He would knock on the old people’s doors on Saturday to ask if they needed anything from the shop. And the next day he would went down the hill to the shop. The shop was far away from the village. He would bring back heavy things for them every time, which made him very tired on his way back. And very often he was still on his way back when the sun had set down.

His friends asked him what he was doing and after some time some of them joined in. It became a habit as time went by. He never asked for money for doing it, but some old people would put some coins in his pocket without telling him. But later when he found them, he would buy something useful for them with the money.

After he went to college, many of these elderly people would ask his mother about him. Only after the conversations did his mother know what David used to do for them. David had never told his mother what he had done!

Now David is a teacher. He often tells his students that helping the elderly is a good tradition that everyone should follow forever.

1.When would David bring back what the elderly needed?

A. On Friday. B. On Saturday. C. On Sunday. D. On Monday.

2.How did David feel when he got back from the shop according to the passage?

A. Angry. B. Hungry. C. Thirsty. D. Tired.

3.What became a habit as time went by?

A. Going down the hill. B. Going to the shop.

C. Carrying heavy things. D. Helping the elderly.

4.We can see from the passage that ________.

A. David is a kind-hearted man B. David is an English teacher now

C. David gets lots of money from the old D. David always gets home late

5.Which of the four is NOT true according to the passage?

A. Some old people would put some money in David’s pocket without telling him.

B. The village where David and the other people lived were very cold in winter.

C. David’s mother knew what his son had done for the old people very clearly.

D. Not only does David help the elderly but also he teaches his students to do so.

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