look around when____the street.a.crossing b.crossed c.to cross d.across 请详细说明理由.
问题描述：
look around when____the street.a.crossing b.crossed c.to cross d.across 请详细说明理由.
答
a crossing
省略,look around when(you are )corssing the street
这是提醒人在过马路时要注意周围,look aroud的动作一定是发生在正在过马路时的,所以是进行时
其他时态不符