The keeper of the spring cleared away the leaves and branches, and wiped away the silt(淤泥) that would _______ have choked and polluted the fresh flow of water.

A．thus

B．otherwise

C．therefore

D．later

根据血药浓度制定的给药方案主要有

A．血清肌酐法

B．重复一点法

C．一点法预测维持剂量

D．常规测定法

E．比例法