问题补充：
The operation room in every hospital has to bacteria of any kind so that the patient being operated on doesn’t get infected.
A. keep free from
B. make it free from
C. to be made free with
D. be kept free from
答案：
A. keep free from
B. make it free from
C. to be made free with
(答案→)D. be kept free from
解析：可联系答.案.网客服索取。
