问题 单项选择题

船体发生纵向弯曲变形和破坏是由于()。

A.局部强度不足

B.总纵弯曲强度不足

C.横向强度不足

D.扭转强度不足

答案

参考答案:B

问答题

       史学界普遍认为,宋元时期是我国古代科技发展的高峰,你是否同意这个观点?请说明理由并简要概括宋元时期科技得到高度发展的原因。

                                                                                                                                                              

                                                                                                                                                              

                                                                                                                                                              

                                                                                                                                                              

                                                                                                                                                              

                                                                                                                                                             

                                                                                                                                                              

                                                                                                                                                             

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