The distance from Xiao Min's home to the library is 4 kilometers.
(2) According to the statistical chart of dotted line on the horizontal axis, Xiao Min walked for 30 minutes.
Her time in the library:
100-30=70 (minutes);
When she got home:
120- 100=20 (minutes).
So the answer is: 4,30,70,20.
We must obey the librarian there.
We must abide by the library rules.
We must abide by the rules of the library.
You are in the library.