今天我们来谈一种SAT写作技巧，就是选择最恰当的语法结构。在SAT写作中，选择合适的语法结构可以使句子意思的表达更为精确和简练。以下原则是在考虑选择何种语法结构时可以参考的原则：

1. 一个句子的主语和谓语动词应该能够反映句子中的最重要的意思。例如：

The situation that resulted in my grandfather's not being able to study engineering was that his father needed help on the farm.

从意思上来分析，上面这句话需要表达的重要的概念是“grandfather's not being able to study”，而在表达这个概念时，原句用的主语是situation，谓语动词是was，不能强调需要表达的重点概念，可以改为下面这句话：My grandfather couldn't study engineering because his father needed help on the farm.

2. 避免频繁使用“there be”结构，例如下面的句子：

There were 25 cows on the farm that my grandfather had to milk every day. It was hard work for my grandfather.

可以改为：My grandfather worked hard. He had to milk 25 cows on the farm every day.

更简洁的句式为：My grandfather worked hard milking 25 cows daily.

3. 把从句改为短语或单词。例如：

Dairy cows were raised on the farm，which was located100 kilometers from the nearest university and was in an area that was remote.

简介的表达方式为：The dairy farm was located in a remote area， 100 kilometers tothe nearest university.

4. 仅在需要强调宾语而不是主语的时候，才使用被动语态。例如：

In the fall， not only did the cows have to be milked， but also the hay was mowed and stacked by my grandfather's family.

本句不够简洁的原因是本句的重心应该是“忙碌的家庭-my grandfather's family”，而使用了被动语态后，仿佛重心变成了cows和hay。下面的表达方式是主动语态，相对来说更简洁一些：In the fall， my grandfather's family not only milked the cow but also mowed and stacked the hay.

5. 用更为精确的一个动词来代替动词短语，例如下面这句话：

My grandfather didn't have time to stand around doing nothing with his school friends. Stand around doing nothing其实可以用一个动词来表达，即loiter：My grandfather didn't have time to loiter with his school friends.

6. 有时两句话的信息经过组合完全可以用一句话来简练地表达，例如：

Profits from the farm were not large. Sometimes they were too small to meet the expenses of running a farm. They were not sufficient to pay for a university degree. 两句话的信息可以合并为下面这句更为简洁的句子：Profits from the farm were sometimes too small to meet operational expenses， let alone pay for a university degree.

通过学习SAT写作技巧，我们了解到了在SAT写作中如何选择最恰当的语法结构。虽然语法的多样性也很重要，但选择最恰当的语法结构仍然是更为重要的考虑因素。