题干

小丽同学在测量盐水密度时,进行下列操作,其中的一步错误操作是:____(填序号),正确的操作顺序应当是____(填序号)

①把烧杯中盐水倒一部分到量筒中,测出量筒中盐水的体积V;

②用天平称出烧杯和剩下盐水的总质量m2;

③把天平放在水平桌上,旋动平衡螺母,使横梁平衡;

④把天平放在水平桌上,拔动游码,使横梁平衡;

⑤用天平测出烧杯和盐水的总质量m1;

小丽在测盐水质量时,出现了如图所示的情况,此时她应进行的操作是:____.盐水的密度为____(用测量的物理量表示).

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答案(点此获取答案解析)

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同类题3

阅读下面短文,掌握其大意,然后从各题所给的A、B、C、D四个选项中,选出最佳选项。

    No one is born a winner. People make themselves into winners by their own 1.

    I learned this lesson from a(n)  2 many years ago. I took the head 3job at a school in Baxley, Georgia. It was a small school with a weak football program.

    It was a tradition for the school's old team to play against the 4 team at the end of spring practice. The old team had no coach, and they didn't even practice to 5the game. Being the coach of the new team, I was excited because I knew we were going to win, but to my disappointment we were defeated. I couldn't 6 I had got into such a situation. Thinking hard about it, I came to 7 that my team might not be the number one team in Georgia, but they were 8me. I had to change my 9about their ability and potential.

    I started doing anything I could to help them build a little  10 .Most important, I began to treat them like 11 .That summer, When the other teams enjoyed their 12 ,we met every day and 13passing and kicking the football.

    Six months after suffering our 14on the spring practice field, we won our first game and our second, and continued to15.Finally, we faced the number one team in the state. I felt that it would be a 16for us even if we lost the game. But that wasn't what happened. My boys beat the best team in Georgia, giving me one of the greatest17my life!

    From the experience I learnt a lot about how the attitude of the leader can 18 the members of a team. Instead of seeing my boys as losers, I pushed and19them. I helped them to see themselves 20 ,and they built themselves into winners.

    Winners are made, but born.