根据意思写出合适的词语
形容忽然明白了。____
下列关于氧气的说法，错误的是（ ）
Tom and his sister ______ to the barbecue last Saturday.They were very happy.
若多项式x2+ax+8和多项式x2﹣3x+b相乘的积中不含x2、x3项，求（a﹣b）3﹣（a3﹣b3）的值．
