Mr. Li taught me ________ in the river when I was a child.

John, you needn't do your work today; you _________ do it tomorrow if you're tired.

The failure of the experiment made us very sad. _________it also taught us a lot.

Don't get off the bus _______ it has stopped.

Many sportsmen are getting ready _______ the 2008 Beijing Olympic Games.

--You aren't a new comer, are you?

--________, do you forget ________ me at the school gate ten minutes ago?

--Where's my school bag, Jim?

--Mother put it in your bedroom this morning, ________?

The number of teachers in our school is larger than ________ of theirs.

--This is _______ useful book, I think.

--So it is, and it's ________ unusual one.

When class began, we stopped ________ to the teacher carefully.