A: Excuse me, do you know where the chemistry lab is?

B: Yes. It’s just on the fifth floor of this b____76____.

A: How often do you do c___77____ experiments there?

B: Twice a week.

A: Can you go there without a t___78___?

B: No. That’s not allowed.

A: What does the teacher often tell you to do when you are doing an e____79___?

B: He often tells us to look c____80____ and follow the i____81____.

A: What will you do when you finish the experiment?

B: We must put e___82_____ back in the cupboards and wash our hands.

A: Right. It is very i___83____ to keep the lab clean.

B: Yes, safe as well. We must turn off the e____84____ before l___85___ the lab.