如图所示，ab为闭合电路的一部分导体，当ab在磁场中运动时，能产生感应电流的是　____ 。

A．垂直纸面向里运动        B．垂直纸面向外运动

C．沿纸面向右运动          D．沿纸面竖直向上运动

理由：　____ 

选词填空，阅读下列短文，用方框内所给单词的正确形式填空

    As a student, what does it mean " to be good"? TheCode of Conduct for Primary and Middle School Students (《中小学生守则》) holds the answer.

    Last year, a new draft (草案) code came____, replacing the old content. There are some important ____. Big phrases like"have deep love for your motherland, the people and the Communist Party of China" are not there anymore. The new code tells students to respect the national flag and national emblem (国徽)____. It also ____students to "know about China's history".

    Also, the new code asks students to "lead alow-carbon (低碳的)____"，"takepart in voluntary work"， and "control the time you spend online". The change on brave actions ____draws attention. The old code told students to act bravely when they saw people ____rules. But the new code asks students to learn to protect ____and ask for help.

    Many teachers are ____to see these changes. Students say they know____to do when they face some problems.

某种温度下，在100g质量分数为20％的硝酸钾不饱和溶液甲中加入10g硝酸钾固体，恰好得到饱和溶液乙，下列说法正确的是(   )