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

be against something • be up against something
be against something —express opposition to smth.: And even
though no one in the audience was against the project, there
was plenty of skepticism.
be up against something —(also: come up against something )
encounter a serious obstacle or problem: But now we are up
against a different kind of health concern — a potential pan-
demic. If the bird flu develops the ability to spread easily be-
tween humans it will be quite dangerous.
be all wet • be wet
be all wet—(U.S. coll.) be completely wrong: If you think
I’m going to take that kind of talk from you, you’re all wet.
be wet—(UK coll.) be unable to make decisions or take firm
actions: Don’t be so wet! Just tell them that you don’t want to
go.
Note: 
Neither expression correlates in meaning with the phrase
be wet behind the ears
—(coll.) be young, naïve, and inexperi-
enced: For a twenty-five-year-old kid, still wet behind his ears,
he got a lot of wisdom from somewhere. Cf.: be dry behind the
ears — be mature or experienced: The three children, barely dry
behind the ears, have taken over running the family dairy.
be ancient history • be history
be ancient history —said of a past event that has lost its orig-
inal impact or importance: For today’s high school students
all of that war is ancient history.
be history —
1
. said of smb. whose career has been brought
to an end: We are familiar with that reference: “He is history
now,” which condemns some poor individual to the rubbish
bin of life. 2. = be ancient history: After reading the two latest
reports, I have to wonder about Bishop Gregory’s assertion
that this scandal is history.
be assured of something • be sure of something
be assured of something —
1
. be guaranteed smth.: General
Franks is assured of a place in history in a country where for-
mer officials are respected even when out of office. 2. have
trust in smth.; be positive about smth.: The king was assured
of the rectitude of the motives on which he had himself acted.
3. be firmly persuaded of smth.: In 
1
4
1
5, Hus was summoned
to defend himself at the Council of Constance, having been
assured of a safe conduct.
be sure of something —
1
. feel confident of smth.: If nothing
occurs to stir the rage of this vindictive madman, I am sure of
victory. 2. = be assured of something 2: The jury are told they
cannot convict unless they are “sure” of the man’s guilt.