These are probably confused with each other more often through haste than through actual ignorance, but “by” is the common preposition in phrases like “you should know by now.” It can also serve a number of other functions, but the main point here is not to confuse “by” with the other two spellings: “’bye” is an abbreviated form of “goodbye” (preferably with an apostrophe before it to indicate the missing syllable), and “buy” is the verb meaning “purchase.” “Buy” can also be a noun, as in “that was a great buy.” The term for the position of a competitor who advances to the next level of a tournament without playing is a “bye.” All others are “by.”
“Cache” comes from the French verb cacher, meaning “to hide,” and in English is pronounced exactly like the word “cash.” But reporters speaking of a cache (hidden horde) of weapons or drugs often mispronounce it to sound like cachet—“ca-SHAY” —a word with a very different meaning: originally a seal affixed to a document, now a quality attributed to anything with authority or prestige. Rolex watches have cachet.
3) CALL THE QUESTION
This is more a matter of parliamentary procedure than of correct English, but people are generally confused about what “calling the question” means. They often suppose that it means simply “let’s vote!” and some even imagine that it is necessary to call for the question before a vote may be taken. You even see deferential meeting chairs pleading, “Would someone like to call for the question?”
But “calling the question” when done properly should be a rare occurrence. If debate has dragged on longer than you feel is really warranted, you can “call the question,” at which time the chair has to immediately ask those assembled to vote to determine whether or not debate should be cut off or continue. The motion to call the question is itself not debatable. If two-thirds of those voting agree that the discussion should have died some time ago, they will support the call. Then, and only then, will the vote be taken on the question itself.
Potentially this parliamentary maneuver would be a great way to shut down windy speakers who insist on prolonging a discussion when a clear consensus has already been arrived at; but since so few people understand what it means, it rarely works as intended.
Chairs: when someone “calls the question,” explain what the phrase means and ask if that is what’s intended. Other folks: you’ll get further most of the time just saying “Let’s vote!”
Calling someone “callous” is a way of metaphorically suggesting a lack of feeling similar to that caused by calluses on the skin; but if you are speaking literally of the tough build-up on a person’s hand or feet, the word you need is “callused.”
5) CALM, COOL, AND COLLECTIVE / CALM, COOL, AND COLLECT
Unless you’re living in an unusually tranquil commune, you wouldn’t be “calm, cool, and collective.” The last word in this traditional phrase is “collected,” in the sense of such phrases as “let me sit down a minute and collect my thoughts.” If you leave out “cool” the last word still has to be “collected.”