题干

X、Y、Z是3种短周期元素,其中X、Y位于同一主族,Y、Z处于同一周期。X原子的最外层电子数是其电子层数的3倍。Z原子的核外电子数比Y原子少1。下列说法正确的是(     )

A:元素非金属性由弱到强的顺序为Z<Y<X

B:Y元素最高价氧化物对应水化物的化学式可表示为H3YO4

C:3种元素的气态氢化物中,Z的气态氢化物最稳定

D:原子半径由大到小的顺序为Z<Y<X

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A

同类题3

从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

Advice for High School Students

    As a person who is graduating from high school very soon, I have some suggestions for students in high school or students who are soon going to be high school students.____ I am sure others can benefit from reading them and will not make similar mistakes like me.

    ____ Do not value first impression highly. Don't dismiss a person or an idea too early just because you immediately get a bad impression. You will miss many opportunities because of that.

    Although something seems bad at the first impression, it does not mean it is bad all the time. Try to give everything a fair chance.

    Don't try to please everybody. There is no way you can please everybody or get everybody to agree with you.____ It is a huge waste of time.

    Have respect for authority. No matter how much you may dislike them, just remember that teachers and parents care about you and they are only doing their jobs.____ Don't argue with them and just obey them.

    Realize a high school is not the real world. The real world isn't a closed environment. ____ What is rewarded in high school such as popularity and agreement is different from what is rewarded in the real world. If high school isn't working out for you, you may find yourself better at handling the real world.

A. Do not be too quick to judge.

B. So just learn to say the word “No” a lot.

C. Listen to their advice and consider it carefully.

D. Many of these are based on regrets that I have.

E. Bad habits are hard to break and remain with you for a long time.

F. Don't spend any effort trying to please others who will never like you.

G. It is a free society where people accept responsibility for their actions.

同类题4

阅读理解

    After years of debate, gray wolves were reintroduced (重新引进) to Yellowstone National Park. Fourteen wolves were caught in Canada and moved to the park. By 2016, the Yellowstone wolf population had grown to more than 170.

    Gray wolves once were seen here and there in the Yellowstone area and other pans of United States, but they were gradually displaced by human development. By the 1920s, wolves had disappeared from the Yellowstone area. They went farther north into the deep forests of Canada, where there were fewer humans around. The disappearance of the wolves had many unexpected results. Deer and elk populations—major food sources(来源) for the wolf—grew rapidly. These animals ate large amounts of plants, which reduced plant diversity(多样性) in the park. With the disappearance of gray wolves, coyote (草原狼) populations also grew quickly. The coyotes killed a great number of red foxes in the park, and completely drove away the park's beavers (河狸).

    As early as 1966, biologists asked the government to consider reintroducing wolves to Yellowstone Park. They hoped that wolves would be able to control the elk and coyote problems. Many framers were against the plan because they feared that wolves would kill their farm animals or pets.

    The government spent nearly 30 years thinking lip a plan to reintroduce the wolves. The U.S. Fish and Wildlife Service carefully monitors and manages the wolf packs in Yellowstone. Today, the debate continues over how well the gray wolf is fitting in at Yellowstone. Elk, deer, and coyote populations are down, while beavers and red foxes have made a comeback. The Yellowstone wolf project has been a valuable experiment to help biologists decide whether to reintroduce wolves to other parts of the country as well.