The way to the library refers to the time from 0 to 60 minutes, and 20 to 40 minutes is the parking time, which means the parking time is
40-20=20 (point)
Zhang Ming stopped for 20 minutes on his way to the library.
(2) As can be seen from the figure,
It takes 120 minutes to get to the library, and the distance from 60 to 100 has not changed. I borrow books from the library, and I'm not on the road, so the round trip time on the road is: 120-( 100-60)= 80 (minutes).
10/80= 1/8 (km/min)
The average speed of borrowing books from the library by Zhang Ming is (1/8) kilometers per minute.