题目内容
The manufacturer stipulates that ______ factory workers receive proper safety training before being assigned to the assembly line.
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The conference was originally scheduled to take place next Monday but it has been ______ until further notice.
It is difficult to determine ______ he is qualified for the job without reviewing his résumé.
All the documents must be kept confidential, so all employees are advised to check that all doors are locked properly ______ leaving the office.
We are currently developing new software that finds mistakes ______ and makes corrections.
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