不得已

不得已 [bù dé yǐ]

1. ■ act against one's will; be forced to; have no alternative but to; have to:

不得已而求其次 have to be content with the second best; have no alternative but to give up one's preference;

不得已而为之 feel constrained to act against one's will; do sth. against one's will; have no alternative but to do sth.;

实在不得已， 她只好请几天假。 She had no alternative but to ask for a few days' leave.

非万不得已不要用这种药。 Don't take this medicine unless it's absolutely necessary.