besureabout的用法及例句

be sure about sth、
It is impossible to be sure about the value of land、
土地的价值是无法确定的、

be sure of 与 be sure about 的区别：

be sure of 确信

例句：She looked over her shoulder to be sure of her footing、她扭头看了看后面以确认自已是否站稳了、

be sure about 对、很有把握

例句：You can be sure about their interest in it、你可以肯定他们对引很感兴趣、