before the ___(close) of the factory ,noise pollution was always a serious problem.
问题描述：
before the ___(close) of the factory ,noise pollution was always a serious problem.
答
close 既是名词也是动词.closing也是名词形式.如果更强调动作含义,往往用后者.我觉得此处都可以,我个人偏爱用closing