副词
副词可以修饰形容词，动词，副词或整个句子。如：
The book is very good.
He runs fast.
She came here quite early.
Certainly I will go with you.
副词变化形式：
• 直接在形容词后加-ly：
careful-carefully, slow-slowly
• 以辅音字母加y结尾的形容词，把y变i, 加-ly：
happy-happily, lucky-luckily
• 有些词形容词和副词的形式相同，不需要做任何变化：
fast, hard, late
• 有些词加上-ly后意思与原词相差很远：
neary-nearly, high-highly, late-lately