to make a very serious promise that something is true
сделать очень серьезное обещание, что что-то правда (sdelat' ochen' ser'yeznoe obeshchaniye, chto chto-to pravda)
"I swear on my life, I didn’t do it!"
"Я клянусь своей жизнью, я этого не делал!" (Ya **klyanus' svoey zhiznyu**, ya etogo ne delal!)
to make a small or funny mistake
to operate smoothly and efficiently
a person who is only your friend when things are good
To be proud and confident even after failure or hardship.
to make a small mistake
to think very hard about something
