表示设备断开和允许进入间隔的信号及电压表的指示等，均不得作为设备（）的根据，应验电。

Laboratory work is your chance to learn science first-hand. It can be fun but you must be careful to prevent injury. Listen closely when your teacher reads and explains the rules before your first lab lesson.

LABORATORY RULES
Throughout the lesson	Do not enter the science lab without the teacher’s permission. No food or drinks are to be allowed in the science lab.
Before the Experiment	Read all instructions carefully before every experiment. Prepare all apparatus (仪器) and arrange them 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 in proper waste baskets.
First Aid	Report all accidents to your teacher immediately. If you spill (溅出) any chemicals onto your body of clothing, wash with plenty of water and report to your teacher.

小题1:Your teacher will probably tell you the rules above        the first lab lesson.

A．before

B．since

C．during

D．after

小题2:Before every experiment, you should       .

A．taste the chemicals first

B．clean all the apparatus

C．read all instructions carefully

D．report all the accidents to the teacher

小题3:When you are not sure how to use all apparatus,       .

A．try them on your own	B．put them back
C．ask your teacher for help	D．read the rules carefully

小题4:It is clear that you can       .

A．bring food into the lab

B．enter the lab anytime

C．smell chemicals as you like

D．learn science directly in the lab

小题5:If you get chemicals on the clothing, you can find ways to solve it in the part       .

A．Before the Experiment	B．First Aid
C．During the Experiment	D．After the Experiment