测量长度的基本工具是 ，测量结果由数值和 组成的。国际单位制中，时间的主单位是 。
刻度尺；单位；秒
此题要求改正所给短文中的错误。对标有题号的每一行做出判断：如无错误，在该行右边横线上画一个勾(√)；如有错误(每行只有一个错误)，则按下列情况改正：
该行多一个词：把多余的词用斜线(＼)划掉，在该行右边横线上写出该词，并也用斜线划掉。
该行缺一个词：在缺词处加一个漏字符号(∧)，在该行右边横线上写出该加的词。
该行错一个词：在错的词下划一横线，在该词下面写出修改后的词。
How I hate act dishonestly in exams! This morning, Henry tried to copy his answers. He whispered to me so that the teacher couldn't hear. I didn't know what to do it. If I didn't show him the answers, he might be mad. Henry is my friend. I really don't want to destroy our friendship. But showing him the answers would be something that went against my beliefs. During an exam, I tried several ways to guard my answers so that Henry wouldn't be able to see it. I moved myself closer to my desk, and I covered my papers with my arms. After the exam, I explained how I was felt to Henry and promised to help him study before the next exam. Henry understood that and I finally able to breathe again.
《中华人民共和国安全生产法》是何时、在什么会议上通过的？自何时起实施？
