现存的爬行动物约有6550多种，分为喙头蜥目（）、（）蛇目和鳄目。
参考答案：蜥蜴目；龟鳖目
It is said that ______ regularly is good for us, for we can know whether we are healthy or not. [ ]
A. examined
B. examining
C. being examined
D. having examined
FPIA分析中标本抗原浓度越高（）。
A.游离的标记抗原越少
B.形成的标记抗原-抗体复合物越少
C.形成的标记抗原-抗体复合物越多
D.发出的偏振荧光越强
E.游离的已知抗体越多
