1 . 听下面一段较长对话，回答以下小题。
1. What's the percentage of travelers only considering jet lag “an unpleasant thing”?

A．Only one third.

B．Almost a half.

C．Over three quarters.

2. What problem caused by jet lag is NOT mentioned?

A．Headache.

B．Exhaustion.

C．Sleep disorder.

3. How many time zones which you cross might make jet lag a real problem?

A．Only one.

B．Two.

C．Over three.

4. Which flying trip might cause more problems according to the talk?

A．From Shanghai to Beijing.

B．From Los Angeles to New York.

C．From New York to Los Angeles.