boast偏中性壹些，除了表示“吹噓”以外，也可以表示正面的“引以自豪”的含義，例如：
She's always boasting about how wonderful her children are.
brag偏口語化，基本都表示貶義，例如：
He's always bragging about how much money he has made.
boast偏中性壹些，除了表示“吹噓”以外，也可以表示正面的“引以自豪”的含義，例如：
She's always boasting about how wonderful her children are.
brag偏口語化，基本都表示貶義，例如：
He's always bragging about how much money he has made.