正确答案: B

②③

题目：在物理实验中，很多时候都需要对相关物理量进行多次测量，其中有的是为了通过多次测量寻找规律，有的是为了通过多次测量提高精度。下面四个实验中哪些是通过多次测量寻找规律的：①用刻度尺多次测量某一物体的长度；②在做“探究凸透镜成像”实验时，多次改变物距观察成像情况；③研究杠杆平衡条件时多次调节钩码的个数及位置；④在做“伏安法测电阻”实验时，调节滑动变阻器，测量对应的多组数据。（ ）。

解析：B

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举一反三的答案和解析：

[单选题]下列句中加点成语使用不正确的一项是( )(2分)

繁华的商业大街上，观光购物的人济济一堂，笑容满面。

[单选题]46．—Let' s go shopping，shall we?—_________

Good idea．

解析：46．A【解析】句意；——我们去购物好吗？回答应该是对该提议的看法。故选A。

[单选题]6．Nice ________you．

to meet

解析：6.B【解析】“Nice to meet you”意为“很高兴见到你”。

[单选题]下列句中的“甲、乙、丙、丁”是名著中的四个人物，依次对应正确的一项是（ ）①在乱石山碧波潭底，孙悟空变作一只螃蟹，偷走了【甲】的辟水金睛兽，随即到芭蕉洞哄骗罗刹女。

甲：牛魔王 乙：外祖母 丙：列夫?托尔斯泰 丁：格列佛

[单选题]．下列安全措施不正确的是

正在使用的家用电器着火，立即用水浇灭

[单选题]Stress is the feeling you get when you're really worried about something． This is the kind of worry that troubles you for hours，or even days．It makes you feel (11)，scared(恐惧的)，or angry． You may find it difficult to eat and sleep，or you might eat and sleep much(12) than usual． Stressing out will lead to serious 'problems like heart illness．(13) not all stress is bad for you． The good kind (14) your body and mind alert(机敏的) and can make you perform better，like when you're giving a speech to your class or running to the finish line．What causes stress? Do you know(15) your dad is worried about the bills，or your mom is unhappy? Because they're stressed out! There are lots of things in your life that ,(16) cause stress-having too much homework，taking a test in a subject that you are not good (17) ，or hearing your parents argue!

upset

解析：Ⅱ．11.D【解析】句意：压力使你感觉心烦、恐惧和恼怒。 其他三项均不合意。

[单选题]物质的用途与性质密切相关。下列叙述错误的是．

因为甲醛能使蛋白质变性，起到防腐作用，所以甲醛水溶液可用于浸泡水产品

[单选题]I’m sorry to keep you waiting.--- Oh, not at all. I ______ here for only a few minutes.

have been