make up one’s mind

make up one’s mind 下定决心，拿定主意

【例句】

◆ We have made up our minds to work hard at chemistry．我们下定决心努力学习化学。 

◆ I haven't made up my mind what to do next．下一步怎么办我还没拿定主意。 

◆ Once she has made up her mind, nothing can change it．她一旦下定决心，什么也不能使她改变。（人教版，必修①，Unit 3）