题干

运用元素周期律分析下面的推断,其中错误的是
①113号元素的单质是一种金属,它的氧化物的水化物不能与强碱反应;②砹(At2)是一种有色固体,HAt很不稳定,AgAt是有色难溶于水的固体;③硫酸锶是难溶于水和盐酸的固体;④H2S比水的还原性弱,但H2S比水的稳定性强;⑤周期表中钠在钾的上方,因此非金属性钠比钾弱,单质的熔点钠也比钾低;⑥第二周期非金属元素(除稀有气体元素)原子半径小,得电子能力强,其气态氢化物的水溶液均呈酸性

A:③④⑤⑥

B:④⑤⑥

C:②③④

D:③④⑥

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B

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    Astronauts on shorter shuttle missions (使命) often work very long days. Tasks are scheduled so tightly that break times are often used to finish the tightly that break times are often used to finish the day's work. This type of scheduled is far too demanding for long missions on the International Space Station (ISS). ISS crewmembers usually live in space for at least a quarter of a year. They work five days on and two days off to mimic the normal way they do things on Earth as much as possible. Weekends give the crew valuable time to rest and do a few hours of housework. They can communicate with family and friends by email, internet phone and through private video conferences.

    While astronauts cannot go to a baseball game or a movie in orbit, there are many familiar activities that they can still enjoy. Before a mission, the family and friends of each ISS crewmember put together a collection of family photos, messages, videos and reading material for the astronauts to look at when they will be floating 370 kilometers above the Earth.

    During their mission, the crew also receives care packages with CDs, books, magazines, photos and letters. And as from early 2010, the internet became available on the ISS, giving astronauts the chance to do some “web surfing(冲浪)”in their personal time. Besides relaxing with these more common entertainments, astronauts can simply enjoy the experience of living in space.

    Many astronauts say that one of the most relaxing things to do in space is to look out the window and stare at the universe and the Earth. Both the shuttle and the ISS circle the planet several times each day, and every moment offers a new view of the Earth's vast land mass and oceans.