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

dark matter • gray matter
dark matter— objects not directly detectable by astronomers,
thought to exist in the universe to account for observed grav-
itational effects: The composition of dark matter is unknown,
but may include new elementary particles.
gray matter—
1
. brownish-gray nerve tissue, especially of the
brain and spinal cord: The researchers found increased gray
matter density in women in the left hemisphere of the brain
associated with language. 2. mental power; intellect: The odi-
ous Krendler, in particular, learns to use his gray matter for,
perhaps, the first time in his life.
dash it • make a dash for it
dash it—(interj.) is used to express one’s annoyance about
smth.: Dash it, Tony … you really ought to be careful.
make a dash for it—(coll.) run away very quickly (to avoid
being caught): We all began to ask each other why he hadn’t
made a dash for it.
date back to something • date from something
date back to something —go back in time to a particular date:
The rare binding of this manuscript dates back to the late
middle-ages.
Note: 
The expression does not correlate in meaning with the
phrase backdate something—
1
. put an earlier date to a docu-
ment than the actual one: The vet backdated the vaccination
dates for horses in an attempt to satisfy Jockey Club rules. 2.
make smth. retrospectively valid: The wage increases are to be
backdated to the first of January.
date from something —be in existence since a particular time:
This building dates from the beginning of the last century.
day and night • day or night
day and night—continually; all the time: We worked day
and night to finish the project before the end of the month.
day or night—at any time whatever: The Internet is the best
shopping mall in the world and one that you can visit day or
night.