（1）a bit和a little意为“一点”，在肯定句中修饰动词、形容词、副词或比较级时可以互换。
I feel a bit/ a little unhappy today.
今天我感觉有点不开心。
Kate jumped a bit/ a little farther than you.
凯特跳得比你远一点。
（2）a bit和a little在否定句中的意思恰恰相反，not a bit=not at all，意为“一点儿也不”；not a little=very much，意为“很，非常”。
She is not a bit tired.=She is not tired at all.
她一点儿也不累。
He was not a little hungry.=He was very hungry.
他很饿。
（3）a bit of+不可数名词=a little+不可数名词，意为“一点儿……”。
There is a bit of/ a little milk in the fridge.
冰箱里有一点儿牛奶。
—He seems _____ ill. Shall we take him to the hospital right now?
—I don't think it matters. Maybe he's caught a cold,he only feels _____ cold.