Complete the sentences with the given words in their proper forms(用所给单词的适当形式填空）
【小题1】Today is my grandfather's ____________(sixty) birthday.
【小题2】We must plant ________ (much) trees and flowers .
【小题3】He is _________ (friend) to us.
【小题4】Look! How ___________ (happy) they are playing!
【小题5】Last Saturday we went to the beach and _________ (make) sandcastles there.
【小题6】This bottle of orange juice ____________ (cost) me 12 yuan
【小题7】We are ___________ (luck) to win the first place.