to promise sb the earth/moon	to promise sb a great deal, often unrealistic
promising artist	obiecujący artysta
to show great promise as	zapowiadać się jako...
oath	a formal promise or an example of taboo language
to be put on/under oath	to swear to tell the truth
to swear	to make a formal promise or to use taboo expressions
bad language, swear words	taboo expressions
I could've sworn	I was absolutely certain
I couldn't swear to it	I am not totally sure
to swear by sth	to use sth and think it is wonderful
to pledge sth	to promise sth, often friendship or money
to vow to do sth	to make a determined decision or promise to do sth
to exchange vows	"wymieniać" przysięgi
New Year's resolutions	postanowienia noworoczne
to turn over a new leaf	to change one's behaviour for the better
made,kept,broken	resolutions,vows,pledges and promises may be...
to bet	to risk money on the unknown result of sth in the hpe of winning more money
stake	the amount of money that you risk
to stake a sum of money on sth	postawic na cos pieniadze
(to put )a wager	(zawrzeć)zakład
to wager that...	założyć się, że...
one's best bet	one's best decision
Don't bet on it!	I think that what you have just said is unlikely to happen
to have a flutter on sth	to have a small bet on sth
to put money/one's life on sth	to be sure that sth will happen