step up
1．increase；accelerate增加；促进Trade has been stepping up recently，since the weather turned warmer．因天气转暖，最近贸易不断增加。
Radio and television have stepped up the tempo of the news．收音机和电视机加快了新闻的传送速度。
2．walk up；go or come near向上走；走近
John stepped up onto the plat form and began to speak．约翰走上讲台开始发言。
3．be promoted晋升；提升
He has stepped up into the management of the firm．他升入了公司的管理部门。
He soom stepped up to the chief executive's chair．不久他就爬上了总经理的位子。