七、An advantage of ~~~ is that + 句子(......的优点是......)
　　例句：An advantage of using the solar energy is that it won‘t create (produce) any pollution.
　　使用太阳能的优点是它不会制造任何污染。

　　八、The reason why + 句子 ~~~ is that + 句子(......的原因是......)
　　例句：The reason why we have to grow trees is that they can provide us with fresh air. The reason why we have to grow trees is that they can supply fresh air for us.
　　我们必须种树的原因是它们能供应我们新鲜的空气。

　　九、So + 形容词 + be + 主词 + that + 句子(如此......以致于......)
　　例句：So precious is time that we can‘t afford to waste it.
　　时间是如此珍贵，它经不起我们浪费。