根据句意用括号中单词的适当形式填空，使句子的意思完整、正确。
There are four ___________(season) in a year．
Birds are________ (sing) . They can make beautiful sounds.
It is sometimes ___________ (fog) in autumn and winter．
Birds in Zhalong are in _______(dangerous)．
Eddie, you used to share food with______( I )．