— Why are you so happy, Henry?— My old friend David is coming to visit me. We haven’t seen each other ______ five years.
We can’t work out the physics problem. Can you tell us ____?
This question sounds _____ than that one.
Health is very _____and every student knows the _____of keeping healthy.
Our country _______ a lot in the last fifty years.
She said she had some trouble ___________ her homework.