1 . 阅读下面短文，在空白处填入1个适当的单词或括号内单词的正确形式。

The Xi’an City Wall is the most complete city wall that has survived China’s long history. It     1     (build) originally to protect the city     2     the Tang dynasty and has now been completely restored (修复). It is possible       3     (walk) or bike the entire 14 kilometers.

We accessed the wall through the South Gate. The wall is 12 meters high and from here you can see streams of people moving inside and outside the City Wall.

After     4     (spend) some time looking at all the defensive equipment at the wall, we decided it was time for some action and what     5     (good) than to ride on a piece of history!

We     6     (hire) our bikes from the rental place at the South Gate. My bike was old and shaky     7     did the job. It took us about 3 hours to go all     8     way around the Xi’an City Wall. Supposedly you can do it in two hours, but we stopped at the different gates and     9     (watchtower) to take pictures or just to watch the local people going about their     10     (day) routines.

2 . If you wear contact lenses (隐形眼镜), you might not know the best way to deal with old ones. Washing them down the sink or flushing them down the toilet is not the way to go. Yet one in five people who wear contact lenses do just that. However, the plastic in their lenses can linger (存留), polluting both water and land.

Rolf Halden, an engineer at Arizona State University in Tempe, and his team created an online survey. More than 400 contact lens wearers took part. The questions asked how many got rid of their lenses inappropriately. About 20 percent — one in five — sent their used contact lenses down sink drain or toilet. Assuming all contact lens wearers in the U. S. do that at the same rate, the researchers then calculated how much plastic would be flushed away each year. Their estimate: 6 to 10 metric tons! That's about the weight of two to three adult African forest elephants. Contact lenses are a tiny part of the world's plastic pollution. But the unique plastic used in contact lenses could make them a big concern.

To figure it out, researchers exposed contact lenses to the microbes (微生物) used to clean wastewater in water-treatment plants. These microbes made the plastics begin to fall apart, but they weren't fully broken down. Instead, they created a lot of tiny pieces called microplastics.

Halden worries that these small plastic bits will cause trouble in the food chain. In water, the plastics from contact lenses sink. Animals could view these tiny bits as food. But because the plastic won't provide them with nutrition, this could threaten the health of animals who dined on it.

And that's already happening. Many studies have shown that corals, larval fish and shellfish are mistaking microplastics for food. Over time, they risk accumulating even higher levels of plastic in their bodies. Also the pollution has already shown up in bottled water, sea salt and fish sold for human consumption.

1. Rolf Halden's survey shows that ________.

A．contact lenses have won popularity with Americans

B．contact lenses have caused a huge part of plastic pollution

C．some contact lens wearers throw away their old lenses improperly

D．many contact lens wearers don't wear their lenses in the proper way

2. What did the researchers find about lenses in water-treatment plants?

A．They could be broken down completely.

B．They could be processed properly there.

C．They couldn't be affected by microbes.

D．Some of them became microplastics.

3. What does the underlined sentence “And that's already happening” in the last paragraph mean?

A．Tiny pieces are entering oceans.

B．Sea creatures are eating microplastics.

C．Animals are causing plastic pollution.

D．Contact lenses are damaging the environment

4. Which one of the following is most probably to be discusssed next?

A．People's eyesight is getting worse and worse.

B．Contact lenses must be banned immediately.

C．Animals in the sea are lacking in nutrition.

D．The impacts microplastic pollution has on human health.