v.i.不及物動詞使(關係)變得不愉快Penny's relationship with Tim began to sour after that argument
adj.形容詞脾氣壞的;乖戾的Tim was in a sour mood because he had no milk to drink
adj.形容詞發酵的Tim could not drink the sour milk
v.t.及物動詞變酸;發酵Penny decided to sour the milk to make pancakes with it
adj.形容詞酸的Some fruits are very sweet, while others are very sour