下列各句中，没有语病的一项是(　　)

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    The Asian elephant has been respected for centuries and is still used today for ceremonies and religious purposes. It is respected, not only because it plays a role in Asian culture and religion, but also because it is a key biological species in the tropical forests of Asia.

    The Asian elephant is the largest land mammal in Asian. It is smaller than the African elephant, with relatively smaller ears. Asian elephants have a single “finger” on the upper lip of the long trunk, while African elephants have a second on the lower tip. A number of adult male Asian elephants have no tooth, and the percentage of males carrying ivory(象牙）is different from only about 5% in Sri Lanka to 90% in south India. Asian elephants keep their ears in constant motion in order to free the heat they produce. The species is reported to have well-developed hearing, vision, and smell , and they are also fine swimmers.

    Asian elephants prefer to convey something to form groups surrounding 6 to 7 related females that are led by the oldest female. Like African elephants, these groups occasionally join others to form herds, although these associations are relatively temporary.

    More than two thirds of the day may be spent feeding on grasses, but large amounts of tree bark, roots, leaves and small stems are also eaten. Crops such as bananas, rice and sugar plants are favored foods. Besides, they need to drink at least twice a day so the source of water is quite important.

    The Asian elephant used to live from modern Irap and Syria to the Yellow River in China at first, but it is now found only from India to Vietnam, with a tiny population in the extreme southwest of China's Yunnan Province. More than 100,000 Asian elephants may have existed at the start of the 20^th century. The population is estimated to have fallen by at least 50% over the last 60-75 years.

    The clock struck eleven at night. The whole house was quiet. Everyone was in bed except me. Under the strong light, I looked sad before a huge pile of troublesome stuff that were called “books”. I was going to have my exam the next day. "When can I go to bed?" I asked myself. I didn't answer; as a matter of fact, I dared not.

    The clock struck twelve. "Oh, dear!" I cried, "five more books to read before I can go to bed!” We pupils are the poorest in the world. Dad does not agree with me on this. He did not have to work so hard when he was a boy.

    The clock struck one. I was quite hopeless now. I forgot all I had learnt. I was too tired to go on. I did the only thing I could. I prayed, “Oh, God! Please help me pass the exam tomorrow. I do promise to work hard afterwards, Amen.” My eyes were so heavy that I could hardly open them. A few minutes later, with my head on the desk, I fell asleep.

日常我们听到的声音是靠 ____传来的，声速跟介质的种类有关，还跟 ____有关．