1.注意由并列连词或等立连词连接的成分在语法形式上是否相同，即都是形容词，或都是介词短语，或都是不定式，或都是动名词，或都是句子等。如：

Symposium talks will cover a wide range of subjects from overfishing to physical and environmental factors that affect the populations of different species.

In the teaching of mathematics, the way of instruction is generally traditional, with teachers presenting formal lectures and students taking notes.

2.注意比较结构中相比较的内容在语法形式上是否相同。如：

It is better to die on one’s feet than to live on one’s knees.

Despite the temporary difficulties, the manager prefers increasing the output to decreasing it.

3.其他具有并列或比较意义的短语。

(1)rather than, let alone 虽不是并列连词，但在结构上连接两个语法形式相同的成分。如：

We are taught that a business letter should be written in a formal style rather than in a personal style.

For the new country to survive, let alone for its people to enjoy prosperity, new economic policies will be required.

(2)如果平行的两个成分在形式上是介词短语，而且介词相同，一般说来第二个介词不要省略。如：

At times, more care goes into the composition of newspaper and magazine advertisements than into the writing of the features and editorials.