题干

有两个人利用斜面共同将木箱拉上汽车,为了提高斜面的机械效率,下列做法中可取的是(   )

A:以较快的速度将木箱匀速拉上汽车

B:以较慢的速度将木箱匀速拉上汽车

C:改由一个人匀速将木箱拉上汽车

D:板长不变,改用光滑的斜面板将木箱匀速拉上车

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答案(点此获取答案解析)

D

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阅读下面两段文字,按要求回答问题。
                                                                                             乡 愁
                                                                                           小时候
                                                                                           乡愁是一枚小小的邮票
                                                                                           我在这头
                                                                                           母亲在那头
                                                                                           长大后
                                                                                          乡愁是一张窄窄的船票
                                                                                          我在这头
                                                                                          新娘在那头
                                                                                          后来啊
                                                                                          乡愁是一方矮矮的坟墓
                                                                                          我在外头
                                                                                          母亲在里头
                                                                                          而现在
                                                                                         乡愁是一湾浅浅的海峡
                                                                                         我在这头
                                                                                        大陆在那头