儿童时期哪个系统发育最迟（）
A.淋巴系统
B.生殖系统
C.神经系统
D.呼吸系统
E.循环系统
参考答案：B
She enjoys________new ways of doing things because she thinks she can get much enjoyment by doing that. [ ]
A. leaving out
B. letting out
C. trying out
D. working out
在应用肿瘤标志物做定量检测时，最重要的是确定决定值。通常将( )最大时的临界值定为决定值
A．敏感性B．特异性C．敏感性+特异性D．精密度E．准确度
