Correct

信誓旦旦

/ xìn shì dàn dàn / 
Strokes

Definition

to make a solemn vow

Example

Definition

pledge in all sincerity and seriousness; vow solemnly; make a solemn vow

1
Xìnshìdàndàn
信誓旦旦
de
地
xǔnuò
许诺

make a serious promise