rain   （名詞）雨
  rain   （動詞）雨が降る
  rainy  （形容詞）雨の・雨の多い
  ＜名詞 rain を用いた文＞
     We have much rain in June in Japan. 
     There is much rain in June in Japan.
     There is a lot of rain in June in Japan.

  ＜動詞 rain を用いた文＞
     It rains much in June in Japan.     
     It rains a lot in June in Japan.     

  ＜形容詞 rainy を用いた文＞
     June is the rainy season in Japan.