I couldn’t listen carefully in our English class this morning as I _________ of the comic book that I read before class.

I felt it hard to keep up with my classmates. But whenever I want to ____________, my teacher always encourages me to work harder.

The box is too heavy to carry. What’s in it?—Oh, it is ________ books.

I felt a little tired the end of the day.[ ]

Not until I began to work ____ how much time I had wasted.