血药浓度下降一半所需的时间为( )。 A．潜伏期 B．持续期 C．失效期 D．残留

___ is ____

A．Seeing… believing

B．Seeing…to believe

C．To see…believing

D．To see…believe

Tom owns ______ larger collection of ______ books than any other student in our class.

A．the; 不填

B．a; 不填

C．a; the

D．不填; the

词汇。

1. Hainan Island is in the ____ (南方的) part of China.

2. She couldn't ____ (接受) our invitation because she was too busy.

3. It's difficult for him to make a ____ (决定) now.

4. They were discussing the problems of western ____ (社会).

5. — Which is the most ____ (传统的) festival of China? 

    — Spring Festival.

双香豆素过量引起的出血可用（）

A.硫酸鱼精蛋白

B.叶酸

C.维生素K

D.尿激酶

E.维生素B₁₂

创卫检查中居民健康知识和健康行为的考核对象和方法是什么？