发展的安全文化，其特点是

When the airplane takes off, the passengers are told to （        ）their seat belts.

Water and air are （        ）to human beings. We can not live without them.

Please （        ）me for my rudeness. I really do not know the custom here.

This is an （        ）that will not be easily forgotten.

Chocolate and ice-cream have different （       ）.

When you study in the United States, usually you have to buy your own health （       ）.

In the class the teacher asked the students to （        ）their bad habits.

If your letter is over weight, you must pay for the （       ）.

The dog （        ）the rabbit but could not catch it.

If you have any problems during your study here, please do not （        ）to call me for help.