题干

火箭上使用的燃料和助燃剂分别是氢气和氧气,人们是用____的方法把氢气液化为液体的.
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答案(点此获取答案解析)

压缩体积

同类题4

阅读下面短文,从每篇短文后所给各题的四个选项(A、B、C和D)中,选出最佳选项。

    Outside her cottage, old Mrs. Taylor was hanging out laundry on a wire line, unaware that some children were hiding in a nearby tree watching her every move. They were determined to find out if she really was a witch.(女巫)

    They watched nervously as she took a broomstick(长柄扫帚)to sweep the dirt from her stone steps. But much to their disappointment, she didn't get on the broomstick and fly off. The old lady only looked up when her hen began to make sounds loudly —signaling that she had laid an egg in the nest on the top of the haystack.(干草堆).

    The old lady put aside her broomstick and walked to the haystack, followed by Michael, a black cat she had rescued from a fox trap. With only three legs, it was hard for Michael to keep up with his mistress. The cat was proof for the children that only a witch would own a black cat with three legs! Crawling further along the branches, they could clearly see the haystack.

Mrs. Taylor was standing on a wooden box with the new-laid egg in one hand. Placing the egg in her pocket, she readied herself to climb down. Then, without warning, the box broke under her and she crashed to the ground. The children were in horror.

“Should we go and help her?” asked Mia.

    “What if it's a trick?” replied Patrick. “She probably knows we're here. Witches know things like that!”

After thinking for a while, Julia said “Anyway, we should go and check whether she is all right.”

Approaching prudently, they could see a wound on the old lady's forehead. She had knocked her head on a stone and was unconscious.

“Go and get Dad,” Mia yelled to her brothers. “Tell him about the accident.”

The boys didn't need another excuse to leave. They ran as fast as they could for help, hoping that Mrs. Taylor would not regain consciousness and turn the girls into frogs.

    Later, in the hospital, the old lady smiled her thanks. “I was so lucky that you lovely children happened to be passing when 1 fell. I must have yelled quite loudly.”

    The children exchanged guilty glances, but were very pleased that she was not a witch after all!

同类题5

阅读材料,完成下列要求。

材料一:“一带一路”是指“丝绸之路经济带”和“21世纪海上丝绸之路”的简称,“一带一路”贯穿欧亚大陆,东边连接亚太经济圈,西边进入欧洲经济圈。无论是发展经济、改善民生,还是应对危机、加快调整,许多沿线国家同我国有着共同利益。历史上,陆上丝绸之路和海上丝绸之路就是我国同中亚、东南亚、南亚、西亚、东非、欧洲经贸和文化交流的大通道,“一带一路”倡议是对古丝绸之路的传承和提升,获得了广泛认同。

 “一带一路”不仅是中国自身的战略构想,更是沿线各国的共同事业——契合沿线国家的共同需求,为其互补互利互惠开启新的机遇之窗。中国周边各国尽管国情迥异,文化不同,但都拥有和平与发展的共同梦想,都希望搭乘中国列车,加快前行。正因如此,“一带一路”这一宏大构想才得以将各国人民的美好梦想相互连接在一起,而中国同各方一道,共商发展大计,共促和平安宁,共圆振兴之梦,也逐渐成为当前亚洲发展的最主要看点之一。

材料二:文化交流是沟通心灵的桥梁,在国际交往中具有不可替代的重要作用。在对外交往中我们要进一步增强文化自觉、文化自信,积极主动做好对外文化交流工作,让世界各国人民更好地感知中国、了解中国。要充分发挥我们的文化优势,讲好中国故事、弘扬中国精神,把一个文明进步、开放包容、繁荣发展的中国展现在世界人民面前。要以永远做学***国的姿态,吸收借鉴世界各国优秀文明成果,博采众长、为我所用,促进当代中国文化实现更大繁荣发展,建设社会主义文化强国。