Step I Ask the Ss to guess about the content of the passage from the title.

Then ask the Ss to judge the right order of stages of inventions.

Step II Get the Ss to comprehend the passage carefully and accurately, and then divide the text into several parts and work out the main idea for each paragraph.

PartⅠ (Para.1) the discovery of the problem of snakes

PartⅡ (Para.2-3) the research on the approaches to solve the problem

PartⅢ (Para.4-6) the attempts to catch the snakes

PartⅣ (Para.7-8) the requirements of getting a patent.

Step III Ask Ss to go over the whole text again and analyze the text in details.

Discuss the following questions:

1.What are the writing techniques of this text?

2.What's the main idea of the text?

3.What should we learn from this text?

4.What' the writing purpose of the writer?

Step IV Comprehending: Finish the exercise1, 2, 3.