存在于链球菌细胞壁上具有群特异性的抗原是（）。 A.SPA B.多糖抗原 C.核蛋白

设A={x|x是小于9的正整数}，B={1，2，3}，C={3，4，5，6}，则A∩（B∪C）=______．

短文改错/Proofreading and error correction

It was the chance of a lifetime to win the first prize on the Story Writing Show. All I had to do was to write a story or present it. My teachers have been telling me how great my writing was. So if they had said was true, I would have a chance of winning the prize. What were better, I had useful help. There was Uncle Chen, gentleman living near my house, who was a very much famous writer. He agreed to reading my story and give me some advices on how to write like a real writer.

9（）

血清学试验是指 （）

A.体外的抗原抗体反应

B.用已知抗原检测患者血清中相应抗体

C.用已知标记抗原检测患者血清中相应抗体

D.用含有已知特异性抗体的免疫血清检测标本中的抗原

E.用含有已知特异性抗原的免疫血清检测标本中的抗体

水泥混凝土抗折强度试验标准试件尺寸为( )。

A．100mm×100mm×400mm

B．100mm×100mm×550mm

C．150mm×150mm×400mm

D．150mm×150mm×550mm

稳定性是测量仪器保持其计量特性随时间恒定的能力。（）