Jack his pet dog everyday. The dog must feel sad when he’s alone all day long.

Both of the skirts are in style this year． –But I think this one is ．

The professor recommends that we ____ the experiment until it is carefully designed.[ ]

Not until his mother came in ________toprepare his lessons.

The story is not easy for students to understand. —I agree with you, ________ it’s not very long.