How happy I am __(see) all my friends again after the long s

How happy I am __(see) all my friends again after the long summer holiday!
What if the radio doesn't work within two weeks?
You __(give)back your money or you can get a new one
When I passed another classroom,I found the students __ (sing) an English song
Li Ming is planning __(have) a trip to Suzhou this coming National Day
Remember __(return) the book to the library next week