1. An elephant can eat up to 400 pounds of food in one day!

up to: as much as; almost

 2. There are some Americans who spend up to eight hours a day watching television.

 3. He spends up to two or three hours on the phone every day at work.

4. A sudden thunderstorm flooded the srteets. The water was up to the top of his tires.

up to: as high as

 8.

A: What’s Roger up to these days?

B: Not much. He lost his job, so he spends a lot of time rollerblading now.

up to: this idiom is used for activity:

What are you up to?

What are you doing?

 9. He walked up to a police officer and asked for help in finding his mother.

walk up to / go up to: to address a person; say something