题干

用一个玻璃瓶装上写有你心愿的纸片,然后盖上盖子并密封,投入江中,就能漂浮在水面上,成为“漂流瓶”.如果漂流瓶从长江漂入大海,漂流瓶所受到的浮力及它露出水面的体积变化情况是(海水密度大于河水密度)(   )

A:浮力变大,露出水面体积不变

B:浮力不变,露出水面体积变大

C:浮力不变,露出水面体积变小

D:浮力变小,露出水面体积变大

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答案(点此获取答案解析)

B

同类题4

阅读理解。阅读下列四篇短文,从每小题后所给的A、B、C、D四个选项中,选出最佳选项。

    The Colonel(上校) asked Ashenden a good many questions and then suggested that he had particular qualifications for the Secret Service. Ashenden knew several European languages and the fact that he was a writer provided excellent cover: on the pretext(借口) that he was writing a book he could, without attracting attention, visit any neutral country.

    It was while they were discussing this point that the Colonel said, "You know you might get material that would be very useful to you in your work. I'll tell you an incident that occurred only recently. Very dramatic. A foreign government minister went down to a Mediterranean resort to recover from a cold and he had some very important documents with him that he kept in a dispatch case(公文箱). A day or two after he arrived, he picked up a beautiful blonde at some restaurant or other, and he got very friendly with her . He took her back to his hotel, and when he came to himself in the morning, the lady and the dispatch-case had disappeared. They had one or two drinks up in his room and his theory is that when his back was turned the woman slipped a drug in his glass.

    "Do you mean to say that happened the other day?" said Ashenden.

    "The week before last ."

    "Impossible," cried Ashenden. "Why! We've been putting that incident on the stage for sixty years, we've written it in a thousand novels. Do you mean to say that life has only just caught up with us?"

    "Well, I can guarantee the truth of the story." said the Colonel, "And believe me, the government has been put to no end of trouble by the loss of the documents."

    "Well sir, if you can't do better than that in the Secret Service," sighed Ashenden, " I'm afraid that as a source of inspiration to the writer of fiction, it's washout(失败)."