Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 30 to 34 

     Arid regions in the southwestern United States have become increasingly inviting playgrounds for the growing number of recreation seekers who own vehicles such as motorcycles or powered trail bikes and indulge in hill-climbing contests or in carving new trails in the desert. But recent scientific studies show that these off-road vehicles can cause damage to desert landscapes that has long-range effects on the area’s water-conserving characteristics and on the entire ecology, both plant and animal. Research by scientists in the western Mojave Desert in California revealed that the compaction of the sandy arid soil resulting from the passage of just one motorcycle markedly reduced the infiltration ability of the soil and created a stream of rain runoff water that eroded the hillside surface. In addition, the researchers discovered that the soil compaction caused by the off-road vehicles often killed native plant species and resulted in the invasion of different plant species within a few years. The native perennial species required many more years before they showed signs of returning. The scientists calculated that roughly a century would be required for the infiltration capacity of the Mojave soil to be restored after being compacted by vehicles.

What is the main topic of the passage?

(29)  ________ brown and black bears, polar bears do not hibernate during the winter.

_________ the water clear but also prevent the river from overflowing.

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 35 to 42 

     Shyness may not seem to be a serious complaint, but for some who suffer from it, it can become unbearable. Even talking to a small group of people you know can seem like an ordeal – it can feel as if you’ve been asked to give a speech on a topic you know very little about to a number of experts. You start to feel hot and shaky, your heartbeats faster, your knees feel weak, you begin to stutter and the whole experience seems to last forever. 

     The fact of the matter is that shyness is something we often recognize in others: blushing is one of the more visible sighs, for example. Yet we do not judge someone harshly because of this. But shyness does mean you are harder to approach, so you become more isolated. As one shy person put it, “It’s like being in a prison, and it’s very hard to break out.”

     Experts on the subject have come up with various possible solutions, and one has been singled out as being the key to success, namely, finding an interest in common with other people. Spending a lot of time on the sidelines watching other people and envying them because they are much more outgoing doesn’t help; remembering that some of the people you envy most are probably shy themselves. The secret is how you deal with it. And experts have come up with four things you can do today to help. Firstly, you can start by listening to other people.  You will find yourself getting interested in what they’re talking about and asking questions, and before you know it, you’ll be behaving a conversation. Secondly, you could try asking neighbors if you can walk their dog. Like children, pets can be excellent icebreakers for conversations with passers-by. Thirdly, try joining a class to learn something like tapdancing or flamenco, where people are likely to laugh a lot. You’ll feel relaxed, and also you’ll be much too busy concentrating on what you are doing to feel shy. Lastly, try telling yourself that it doesn’t matter if you say or do something silly. Most people make a fool of themselves every so often, and it’s not the end of the world if you do. 

One of the symptoms of shyness in a stressful situation is _________