If you cannot come to the meeting, please let us know ______ so that we will cancel your hotel booking.

You are more likely to ____ what you want if you know how to make necessary _____ in a new environment.

After_____a11 the apples，he____ the biggest one in the basket and handed it to me．

These are all ________houses for the homeless.

This is a very serious matter and the Chinese Academy of Sciences is trying to             public awareness about it.