导读：上期我们向大家介绍了灵活使用“There be”结构和准确使用比较结构。本期继续向大家写好句子的另外两种办法。

三、表达原因结构
【考生病句】
1．The real reason to our failure is not far to seek.
2．The reason for this is because he wants to earn plenty of money without
working hard.
【正确表达】
1．The real reason for our failure is not far to seek.
2．The reason for this is that he wants to earn plenty of money without working
hard.
【点评】以上两个病句分别引自四级考试考生作文。从遣词造句上看，这两位考生具有一定写作能力，not far to seek, plenty of money以及without working hard均运用正确、恰当。不足之处是第一位考生不知道reason不与to搭配而应接介词for，第二位考生犯的错误比较典型，就是用because引起表语从句，because这个词不能引起表语从句，应改用that才正确。
掌握好表达原因结构是十分重要，几乎所有写作涉及到写原因。四级考试写作文体基本上是议论文，而议论文基本模式是摆事实、讲道理，而讲道理就是说明原因。英语中用来表达原因的词和词组有很多，例如：as , because, since, seeing that, considering that, now that等。
1. Now that we have seen these great achievements with our own eyes, we feel more
proud than ever of our country.
2. Since we live near the sea, we enjoy a healthy climate.
3. Pollution is still a serious problem, not that we don't have the ability to solve it, but that
some people have not realized the consequences of the problem.
除了上述例句外，英语中还有很多或易或难表达原因结构。我们在进行写作训练时候，不能满足于一知半解，要讲究书面语言正确性和准确性。比如，because是常用于引导原因从句连词，语气最强，表示直接原因，若because置于句首，后面的句子不能再用so。用as引导原因从句语气较弱，所说明原因是附带，而since表示原因暗示着是稍加分析之后才能推断出来原因。

四、否定结构
【考生病句】
1.Some people think we needn't to worry about fresh water.
2.Nowadays many people don't like to go to the movies, too.
【正确表达】
1.Some people think we needn't worry (或don't need to worry) about fresh water.
2.Nowadays many people don't like to go to the movies, either.
【点评】病句1的错误在于该考生混淆了need作为情态动词和作为实义动词的用法。need作为情态动词时，主要用于否定句，后面动词不带to； need作为实义动词时，可用于肯定句、否定句和疑问句，don't need to worry 中to worry作don't need的宾语。病句2的错误在于该考生混淆了too和either的区别， too, also只能用于肯定句，而either只能用于否定句。