单项选择题 听力原文： Human population near the equator have evolved dark skin over many generations because of exposure to the fiercest rays of the sun. A similar phenomenon has also occurred in other parts of the animal kingdom. The African grass mouse is a good example. Most mice are nocturnal, but the African grass mouse is active during daylight hours. This means that it spends its days searching for food in the semi-dry bush in squired habitats of eastern and southern Africa. Its furry stripe's like a chipmunk's, which helps it blend in with its environment. Because it spends a lot of time in the intense tropical sun, the grass mouse has also evolved two separate safeguards against the sun's ultraviolet radiation. First, like the population of humans in this region of the world, the skin of the grass mouse contains lots of melanin, or dark pigment. Second and quite unusual, this mouse has a layer of melanin pigmented tissue between its skull and skin. This unique cap provides an extra measure of protection for the grass mouse and three other types of African mouse, like rodents that are active during the day. The only other specie scientists have identified with the same sort of skull adaptation is the white tent-making hat of the Central American tropics. Although these bats sleep during the day, they do so curled up with their head exposed to the sun.What is the speaker mainly discussing?A．The adaptations of the African grass mouse to its environment.B．The sleeping habits of the African grass mouse.C．The effect of intense sunlight on the diet of the African grass mouse.D．The habitat of the African grass mouse.

单项选择题 客户在从事融资融券交易期间，可能面临的风险或损失包括（）。Ⅰ.融资利率或融券费率大幅降低，客户将面临融资融券成本增加的风险Ⅱ.担保物被强制平仓的风险Ⅲ.因标的证券终止上市，被证券公司提前了结融资融券交易的风险Ⅳ.因融资融券标的证券范围调整，被证券公司提前了结融资融券交易的风险

单项选择题 听力原文： A number of insects rely on leaping or jumping as a way of escaping from enemies. Grasshoppers probably have the most remarkable jumping ability of all these insects. If we think of it in human terms, a grasshopper's high jump is like a human jumping over a five story building. Imagine that a person jumping over a five story building. Welt, we'll take a look at the structure of grasshopper's leg to see why it's able to jump so well, but first I wanna talk about the sensory organ that tells grasshoppers when to jump in the first place. En, OK, a grasshopper has two sensory organs located at the end of its abdomen. Whenever these organs sense of change in air pressure which might be produced by an enemy approaching, an impulse is transmitted to the legs, this first impulse deactivates the nerves that control normal working and sets the grasshopper's jumping muscles into a sort of pre-jumping position. Now at this point, if the sensory organs don't detect additional air pressure changes, the jumping muscles relax and a grasshopper goes back to its normal walking. But if the organs continue to send danger, another set of impulses put the jumping muscles in motion. The distance of the jumping is determined by just how many impulses are transmitted in the second set, the more impulses the longer the jump. OK now let's see why the grasshopper can jump so far.Whet does the professor mainly discuss?A．How grasshoppers find food.B．How grasshoppers fight other insects.C．How grasshoppers communicate with each other.D．How grasshoppers escape from danger.