为了更好地说明这个问题，我们再看几个纯英文写作中的例子。

String of Main Clause:

In recent years computer prices have dropped, and production cost have dropped more slowly, and computer manufacturers have had to struggle, for their profits have been shrinking.

Revised:

Because production costs have dropped more slowly than prices in recent years，computer manufacturers have had to struggle with shrinking profits.

修改前的句子更像汉语的流水句（run-on sentences)，修改后用 because使句子成为主从复合句，并把两个短句（斜体部分）变为短语，融入两个主句，结构更加紧凑。

并列的短句对英文来说单调乏味，如果把有些句子变为从句、短语或单词，句子将更加活泼。例如：

Monotonous:

The moon is now drifting away from the earth. It moves away at the rate of about one inch a year. Our days on earth are getting longer, and they grow a thousandth of a second longer every century. A month will someday be forty- seven of our present days long, and we might eventually lose the moon altogether. Such great planetary movement rightly concerns astronomers, but it need not worry us. It will take 50 million years.

Revised:

The moon is now drifting away from the earth at the rate of one inch a year. At the rate of a thousandth of a second every century，our days on earth are getting longer. A month will someday be forty-seven of our present days long，if we don't eventually lose the moon altogether. Such great planetary movement rightly concerns astronomers, but it need not worry us. It will take 50 million years.

句子可以变为短语。

修改前：

Although production costs have declined, they are still high. Costs, which include labour and facilities, are difficult to control.

修改后：

Despite some decline, production costs are still high. Costs, including labour and facilities, are difficult to control.

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