a number of， the number of。cause 指造成某一事实或现象的直接原因，后接of sth./doing sth，reason用来解释某种现象或结果的理由，后接for sth./doing sth. the reason for being late。
Unit1 Playing Sports Topic1 【重点单词】1. healthy(同义词)fit(名词)health2. win(过去式)won(名词)winner 3. ski(现在分词)skiing 4. famous(比较级)more famous5.
