各种灭菌后的内窥镜、活检钳和灭菌物品不得检出（）。
A．铜绿假单孢菌
B．致病微生物
C．细菌繁殖体
D．任何微生物
E．细菌芽孢
参考答案：D
从数-6，1，-3，5，-2中任取三个数相乘，则其积最小的是（ ）
A．-60
B．-36
C．-90
D．-30
Questions refer to the following graph. 1977～1978 TEXTB()OK INVENTORY FOR SCHOOLS X AND Y BY YEAR OF PURCHASE (as a percent of the 1977～1978 inventory) Note：All books were purchased new on July 1 of each year.
How many of the inventoried textbooks were purchased by the two schools combined during the years 1974, 1975, and 1976
