( )IEC和ITU是目前国际上最普遍的标准。
A．ISO
B．OTC
C．UFO
D．UN
参考答案：A
解析： ISO是综合性的标准，后两个是专业性的。
Not until they left school ____how much their teachers loved them and helped them.
A．that they realized
B．had they realized
C．when they would realize
D．did they realize
抗HBe(+)的意义是( )
A．急性乙型肝炎、慢性乙型肝炎或无症状携带者B．慢性乙型肝炎C．感染过乙型肝炎D．接种过乙肝疫苗E．乙型肝炎恢复期
