Children must be to serve（服务） their country when they grow up.
A. sentenced
B. preferred
C. educated
D. devoted
网友回答
A. sentenced
B. preferred
(答案→)C. educated
D. devoted
解析：动词辨析。Sentence sb to判处某人…罪；educate sb to do sth教育某人做某事；devote …to…致力于…（to是介词）。句意：孩子们必须被教育长大以后要为人民服务。故C正确。