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For instance, when I was in high school, I always ate in the restaurant because I didn’t have enough time to cook at home. At that time, I was crazy for hamburger and ice-cream. Unfortunately, I put on weight fast and I became a fat girl. After then, I realized I should change my eating habit, so I began to save time for cooking and no longer went to restaurant. Three months later, I successfully lost weight.
这是一个没有语病，条理清晰，叙事完整的例子，也能够支持自己在家做饭更健康这一论点。那么问题在哪儿呢?大家有没有发现，在这个例子中，所有句子的主语都是“I"。除此之外，作者用到的句型是很单调的，大部分都是带有状语从句的句式结构。而在
Take my experience in high school as an instance. Frequently, I dined out with friends in restaurants near school, which helped us save much time from cooking for studies and social activities. However, as the food served in restaurants, such as hamburger and ice-cream, was high in calories, I put on weight fast. The increasing weight warned me off fast food and encouraged me to cook at home. Since then, the homemade food enables me to keep fit.
在这段改写中，增添了“which”引导的定语从句，插入语举例子“such as”，转折副词“however”等，而且以“I”作为主语的句子减少到了两个。这样一来我们就达到了独立写作评分标准中，最高原始分5分的标准之一——demonstrating syntactic variety即句式多样化。既然明确了问题所在和目标，我们再来探讨一下解决方案。
如果你细心读到了这里，是不是想到了一个词——“paraphrase”(同义转述)。没错，句式多样化的重要前提就是有能力用不同的句式来表达同样的意思。平时的练习中，我们可以通过修改自己的文章来练习这个能力。但是在考场上，我们并没有重新改写句子的时间，必须尽量一次写好。也就是在完成段落的过程中，有意识的去变换句式。要做到这一点，我们必须熟练的掌握多个常用的句式。那常见句式有哪些?
形式主语 ✔
There be…✔
定语从句 ✔
各类状语从句 (时间，地点，原因，目的，结果，条件，让步等)✔
强调句 ✔
not only, but also ✔
副词和介词短语 ✔
分词做状语 ✔
主语从句 ✔
非谓语 ✔
建议大家如果发现自己在同一段落中，同一句式连续运用两次了，就强迫自己必须变换一下吧。