In reading science, a heading (标题)often gives a clue (线索)to a problem that is going to be discussed .Getting the problem clearly in your mind is the first step to take in studying such material. You are advised to do this in reading science articles.

1. Read the title and think about it .

2. Read all of the headings .You should get a clear idea of what the problems are without reading anything but the headings.

3. Next , read the article all the way through carefully. Each time you come to a heading that names a problem, read the paragraphs under that heading to find out : 1. more information about the problem; 2.how the problem may be met .

This passage offers advice on _______.