问题补充：
He did the right thing for some fresh air even in cold winter.
A. to keep the chidlren from going out
B. to prevent the childern from going out
C. to keep the children going out
D. to prevent the children going out
答案：
A. to keep the chidlren from going out
B. to prevent the childern from going out
(答案→)C. to keep the children going out
D. to prevent the children going out
解析：只有C项表示“使孩子们保持不断走出去…”, 其它都是:使…不能出去的意思.
