A dictionary of Confusable Phrases: More Than 10,000 Idioms and Collocations

build a fire under someone • burn someone at the
stake
build a fire under someone —(also: light a fire under someone)
do smth. to motivate or stimulate a person; make smb. work
better or harder These students are incredibly motivated. You
don’t have to build a fire under them.
Note: 
a) The expression does not correlate in meaning with
the phrase throw someone into the frying pan—(U.S.) place
smb. with insufficient training into a serious predicament, as-
suming he will adapt to the situation: They threw me into the
frying pan. I was off to Japan for the first time in my life and
not a soul did I know, and not a word of Japanese.
b) The expression is not equivalent in meaning to the phrase
keep someone’s feet to the fire
—(also: hold someone’s feet to the
fire) pressure a person to undertake smth.: We have to continue
to keep Kerry’s feet to the fire and remind him of his promises,
and continue to keep his feet to the fire on certain issues.
burn someone at the stake —reprimand or scold a person se-
verely: Stop yelling. I made a simple mistake, and you’re burn-
ing me at the stake for it.
See also: burn someone down / burn someone up.
build bridges with someone • burn bridges with
someone
build bridges with someone —try to make new friends or es-
tablish cooperation with an opponent: We must work with
leaders of these countries and build bridges with them — both
economically and politically.
burn bridges with someone —do smth. that makes former re-
lationship with smb. difficult or impossible: Robb has moved
considerably leftward, and he has burned bridges with many
leaders in the state.
build up something • build up to something
build up something —
1
. increase or develop smth. steadily:
You must now build up your strength after your illness. 2.
praise or promote smth.: An advertising agency can build up
a product so much that everyone will want it.
build up to something —lead up to smth. gradually or indi-
rectly: You could tell by the way she was talking that she was
building up to something unpleasant.