rainy是形容詞，一般做定語，不作謂語，意思是“下雨的；多雨的；為雨所淋濕的；含雨的”。raining是動名詞，既可以做定語又可以做謂語，意思是“雨；雨水；雨季；下雨；降雨”。

raining

1.It was raining when we set out. 我們出發時正下著雨。

2.Yesterday the radio forecast drizzle,and today it is indeed raining. 昨天預報有小雨，今天果然下起來了。

3.It's raining hard. 雨下得正急。

4.It's raining rustlingly. 雨刷刷地下起來了。

5.Hurry in,children.It's raining! 孩子們，快進來，下雨啦！

rainy

1.They walked along the promenade on a rainy night. 他們在一個雨夜沿著海濱道散步。

2.The rainy season in the Andes normally starts in December. 安第斯山區的雨季通常在12月份來臨。

3.The rainy season has ended at last. 雨季總算過去了。

4.We may expect muggy weather when the rainy season begins. 雨季開始時，我們預料有悶熱的天氣。

5.In the rainy season things get damp easily. 雨季里東西容易返潮。