___ we know some basic knowledge concerning AIDS, we can protect ourselves from being infected.
catch the first bus, he got up very early this morning.
The number of people invited to the party _____ sixty, but a number of them ______absent.
He likes to help others ________ he is very busy.
Mr. Smith will ________ in the movement.
I can not spend ________ money on the car which is ________ expensive for me.