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问题 选择题

如图所示，均匀介质中两波源S1、S2分别位于x轴上的x1=0、x2=16m处，质点P位于x轴上的x3=4m处。t=0时刻，两波源同时由平衡位置开始向上振动，振动周期T=0.1s，传播速度均为v=80m/s。波源S1的振幅A1=3cm，波源S2的振幅A2=4cm。则从t=0到t=0.35s时间内质点P通过的路程为

A．98cm

B．14cm

C．56cm

D．68cm

答案

答案：D

改错题

A little girl who lived in a simple and poor house on a hill. Usually she might play in the small garden. She could see over the garden fence and across the valley the wonderful house with shining golden window high on another hill. Since she loved her parents and her family, she desired to live in such a house and dream all day about how wonderful and excited it must feel to live there. At the age when she gained some basic skill, she begged her mother to a bike ride outside the garden. Her mother finally allowed her to go. Down the hill and cross the valley, the girl rode to the gate of the golden house. As she got︿ her bike and put it against the gate post, she focused on the house. She was disappointed when she found all the windows were rather dirty.
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单项选择题 A1型题

胃大部切除术后发生残胃癌的最短时间是术后（）

A.1年

B.5年

C.10年

D.20年

E.15年
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