we must be careful when we cross the street.是什么从句?when 后面为什么

be careful to cross the street when we meet heavy ______(tra We must be careful when you go _____（cross） the road. you must be careful when you cross the street中可以用if替代when吗 So we must be careful when we use the Internet. We must be careful when we（ ）the road. You must be careful when you cross the street.改为祈使句 you must be careful when you cross the street.(同义句) Be careful when you cross the street.为什么用cross而不用across? 填空 we must be careful when we___ the road 分析句子成分 When we cross the street,we must pay attention to the 分析句子成分,When we cross the street,we must pay attention to the 连词成句：cross,be,the,when,careful,you,street