to promise solemnly, often in a formal way
faire une promesse solennelle, souvent de manière formelle (faire une promesse solennelle, souvent de manière formelle)
"He swore an oath to serve his country faithfully."
"Il prêta serment de servir son pays fidèlement." (Il **preta serment** de servir son pays fidelement)
a sudden and significant progress
To achieve something very difficult or seemingly impossible.
to design or aim something for a particular group
To speak honestly or openly.
to improve one’s effort or performance
to start having doubts about a decision you have made