老年人的肋软骨钙化，弹性降低致胸（）。

Directions:

Suppose you are a college student on a school campus or an employee in a company. Recently you noticed that some people never paid attention to the signs on a garbage can that say it is desirable to deal with wastes separately. Now you are going to make a conservation campaign speech at a party. And your speech should include:

1) the present situation,

2) and your suggestions.

Write your letter in no less than 100 words. Write it neatly on ANSWER SHEET 2.

Do not sign your own name at the end of the letter, use "Li Ming" instead.

Do not write the address.