题目内容：

Lab work is fun but you must be careful. Listen carefully when your teacher reads and explains the rules before your first lab lesson.

LAB RULES
Throughout the lessons	* Do not enter the science lab without the teacher's permission(允许). * No food or drinks are to be allowed in the science lab.
Before the Experiment	* Read all instructions carefully before every experiment(实验). * Prepare all apparatus(仪器)and put them in right places so that you will not knock them over while doing the experiment.
During the Experiment	* If you are unsure of how to use any apparatus or how to operate, ask your teacher for help. * Never smell or taste chemicals unless your teacher gives permission.
After the Experiment	* Wash all apparatus after use and return them to the places where they were. * Throw waste materials into proper waste baskets.
First Aid	* Report all accidents to your teacher immediately. * If you spill any chemicals onto your body or clothing, wash with plenty of water and report to your teacher.

1.You must know the LAB RULES ______ the first lab lessons.

A. before         B. since          C. during         D.after

2.It is necessary for you to ______ before every experiment.

A. read all instructions carefully       B. take enough food and drinks

C. smell chemicals immediately           D. talk with your classmates.

3.If you are not sure of how to use any apparatus, ______.

A. read the rules carefully                  B. try them again and again

C. ask your teacher for help                 D. return all apparatus to the places where they were

4.The underlined word “spill” means ______.

A. 照射           B. 伤害           C.摔下          D.溅出

5.When you are in the science lab, you mustn’t ______.

A. be careful in order to prevent injury         B. listen carefully when your teacher explains the rules

C. taste chemicals without the teacher’s permission   D. throw waste materials into proper waste baskets