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.
　　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，我们经不起浪费它。