用于It + be + 时间段 + before...句型中,意思是“在„„之后才„„”.例如：It will be five years before I come back.我五年后才能回来.
几年后我才好好使用它.Our breaks last for 30minutes at least and we do everything we planned��last ��ô�������� ȷ���������˼����ϣ����ɣ�����