某中心地能维持供应某种商品和劳务所需的最低购买力和服务水平被称为()。 A.需求门槛

递延年金是指在开始的若干期没有资金收付，然后有连续若干期的等额资金收付的年金序列。（）

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

Mary, aged 26, knows English and Japanese. Which job can be given to her()

A. Driving for Capes Taxi.

B. Working for China Airlines.

C. Teaching at Instant Languages Ltd.

D. None of the above.

关系数据模型有许多优点，但下面所列的条目中________不是它的优点。

A．结构简单

B．适用于集合操作

C．有标准语言

D．可表示复杂的语义

什么是供水能力？

肺炎链球菌感染引起（）

A．小叶性肺炎

B．干酪性肺炎

C．大叶性肺炎

D．肺气肿