6.听第10段材料,回答第17-20小题.
17.Why doesn't the speaker suggest buying frist aid boxes?
A.They don't contain enough supplies.
B.They are not always suited to our needs.
C.They are too expensive.
18.What does the amount of basic medicine in the first aid box depend on?
A.The size of one's family or group.
B.The space in the first aid box.
C.The habits of one's family or group.
19.When is a lightweight frist aid box particularly important?
A.When our doctor isn't very well.
B.When someone in the family is seriously ill.
C.When we take a trip away from home.
20.What does the last tip mention?
A.Finding as large as a bag as possible.
B.Taking basic medical supplies others than medicine.
C.Including other things like emergency phone numbers.