17. How many lab sessions will the students have every week?
A. One
B. Two
C. Three
18. What are the students allowed to wear in the lab?
A. Long scarves
B. Loose clothes
C. Tennis shoes
19. Why should the students avoid mixing liquid with paper?
A. It may cause a fire
B. It may create waste
C. It may produce pollution
20. What does the speaker mainly talk about?
A. Grades the students will receive
B. Rules the students should follow
C. Experiments the students will do
B. Rules the students should follow