产生50%最大效应时的剂量（）.
A．极量
B．最小有效量
C．半数有效量
D．治疗量
E．最小中毒量
参考答案：C
用所给词的适当形式填空。
1. Please give ________ (he) the cinema ticket.
2. Daming always likes to wear a pair of ________(trainer).
3. Are they those ________ (child) uncle and aunt from America?
4. Miss Yang and her mother ________ (not watch) TV at night.
5. Let's ________ (send) a card to Rita at her birthday party.
百联OK卡的积分有效期为几年？
