【单选题】I met Kate on ___________way home yesterday. [ ]
【单选题】Kate met a lot of problems _____ she was going over her lessons.
【单选题】Was it in the reading-room ______ you were reading a magazine _____ Kate met you? [ ]
【单选题】Kate and Lenny ______ and kissed each other when they met again after ten years.
【单选题】筛选ALT正常,HBV全阴性者180名,单抗HBs低水平者85名,5-9岁小学生作为研究对象,用随机数字表分成两组。在研究对象和研究者都不了解分组情况条件下,一组接种国产疫苗,一组注射安慰剂,接种9年后检测,发现疫苗组HBV人年感染率为1.72%,安慰剂组为9.25%。本实验采用的盲法方法是()