In spoken English, forms of be are often shortened, for example ‘I am’ is shortened to ‘I'm’ and ‘was not’ is shortened to ‘wasn't’.
在英语口语中，be经常使用缩合形式。如，I am 略作 I'm, was not 略作 wasn't。
be 基本解释
be
动词是; 有，存在; 做，成为; 发生
助动词用来表示某人或某物即主语本身，用来表示某人或某物属于某一群体或有某种性质
be
