The following are three ads.

Driver Wanted

1. Clean driving license

2. Good-looking

3. Age over 25

Apply (申请) to: Capes Taxi, Shenzhen

Tel: 0755-6561382

Air Hostess(空姐) Wanted

1. Age between 20 and 33

2. Height from 1.6m to 1.75m

3. Two foreign languages

4. College graduate

Apply to: China airlines, Beijing

Tel: 010-88488970

Teacher Needed

For private language school

Teaching experience necessary

Apply to: Instant Languages Ltd, Dalian

Tel: 0411-4313861

If you want to work in the south, you can apply for a job as （）.

A．a driver

B．an air hostess

C．a teacher

D．all of the above

按送风方式不同，烧结方法分为哪几种？