按病情程度将肠梗阻分为（）。
A.完全性肠梗阻
B.急性肠梗阻
C.不完全性肠梗阻
D.慢性肠梗阻
E.单纯性肠梗阻
参考答案：A, C
31．—Can you tell me what time the flight to Detroit leaves?
—I'm sorry, but it ______．
A．has been canceled
B．had been canceled
C．has canceled
D．had canceled
用于定量的参数是
A．色谱峰高或峰面积B．死时间C．色谱峰保留时间D．色谱峰宽E．色谱基线
