— David, your mother’s birthday is _____. Let’s think about how to celebrate it. —OK, Dad.
---I am sorry to have kept you ___________. ---It doesn't matter. I've just come.
The number of students in our school_________ more than 2000.
At the science museum,the boys and girls get to know__________.
The more you smile, the ___________ you will feel.
We should study the new traffic rules and 1earn how___________ ourselves.