题干

如图,在灭火抢险的过程中,消防队员有时要借助消防车上的梯子爬到高处进行救人或灭火作业.为了节省救援时间,在消防车向前前进的过程中,人同时相对梯子匀速向上运动.在地面上看消防队员的运动,下列说法中正确的是(   )

A:当消防车匀速前进时,消防队员一定做匀加速直线运动

B:当消防车匀速前进时,消防队员一定做匀速直线运动

C:当消防车匀加速前进时,消防队员一定做匀变速曲线运动

D:当消防车匀加速前进时,消防队员一定做匀变速直线运动

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答案(点此获取答案解析)

B,C

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根据短文内容,选择最佳答案。

    He was the baby with no name. Found and taken from the north Atlantic 6 days after the sinking of the Titanic in 1912, his tiny body so moved the salvage (救援) workers that they called him “our baby.” In their home port of Halifax, Nova Scotia, people collected money for a headstone in front of the baby's grave (墓), carved with the words: “To the memory of an unknown child.” He has rested there ever since.

    But history has a way of uncovering its secrets. On Nov. 5, this year, three members of a family from Finland arrived at Halifax and laid fresh flowers at the grave. “This is our baby,” says Magda Schleifer, 68, a banker. She grew up hearing stories about a great-aunt named Maria Panula,42, who had sailed on the Titanic for America to be reunited with her husband. According to the information Mrs. Schleifer had gathered, Panula gave up her seat on a lifeboat to search for her five children -- including a 13-month-old boy named Eino from whom she had become separated during the final minutes of the crossing. "We thought they were all lost in the sea," says Schleifer.

    Now, using teeth and bone pieces taken from the baby's grave, scientists have compared the DNA from the Unknown Child with those collected from members of five families who lost relatives on the Titanic and never recovered the bodies. The result of the test points only to one possible person: young Eino. Now, the family sees no need for a new grave. "He belongs to the people of Halifax," says Schleifer, "They've taken care of him for 90 years."

    Adapted from People, November 25, 2002