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The teacher told her students to double check their answers before handing in the exam.
They double checked the doors and windows before leaving for vacation.
You need to double check the postage on the letter before you drop it in the mail.老师告诉学生们,交卷之前应该反复检查自己的答案。
他们出门渡假前,反复检查是否锁好了门窗。
大家在寄信之前需要仔细核查邮资是否贴够了。