激活B细胞产生抗体过程中依赖T细胞的辅助的抗原称为

A、完全抗原

B、半抗原

C、TI-Ag

D、TD-Ag

E、共同抗原

科举制开始于哪个朝代？

A.唐朝

B.隋朝

C.宋朝

D.元朝

任何一个儿童的动作发展总是沿着抬头一翻身一坐一爬一站一行走的方向进行。()

为了探讨FLX和OFX两种药物对泌尿系感染的疗效，研究者选择了120例该病患者，随机分为服用A药组和服用B药组，采用盲法观察疗效，以确定两种药物哪个疗效更好。这种研究方法是

A、比较试验

B、观察试验

C、临床试验

D、预防试验

E、干预试验

Which of the following italicized phrases is INCORRECT？

A．I can carry as much paper as you can.

B．He is as busy as a bee.

C．She is as a good teacher as your father.

D．He was as experienced as his brother was green.

You can go to a travel agency and ask for a holiday______.

A．introduction

B．advertisement

C．book

D．brochure