下消化道出血患者的粪便是（）
A.米泔水样便
B.暗红血样便
C.白陶土样便
D.柏油样便
E.果酱样便
参考答案：B
—I like Spots World. How about you?
—I ________ you. [ ]
A. agrees with
B. like
C. agree
D. agree with
能唯一地标识实体的属性的______称为关键字。
A．组合
B．排列
C．元组
D．集合
