1、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。
2、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。
