assure

/əˈʃɔːr/

to tell someone confidently that something is true, especially so that they do not worry

(尤指为消除其忧虑而)确定地对…说，向…保证，使确信;让…放心

She assured him (that) the car would be ready the next day.

她向他保证说他的车第二天就能修好。

You can rest assured that I shall be there as promised.

你放心，我答应了就一定会到的。