1. Tall and High Tall – greater in height than the average person, structure, etc. E.g. Laurie is very tall for her age. High – rising or extending upward a great distance. E.g. Mt. Everest is a very high mountain. RULE: We use tall for people and high for things/objects.

2. Than I/Than me? When the word than comes before a pronoun, what comes next? I, or me? The answer is both. E.g. My mom loves our dog Prince more than I. (...more than I do) My mom loves our dog Prince more than me. (She loves our dog more than she loves me!)

3. That or Which or Who? Use who to refer to persons, not which. E.g. They are the ones who left early. The girl who [not that or which] sang “The Prayer” was named Singer of the Year. That, though generally used to refer to things, may be used to refer to a group or class of people. That introduces essential clauses; which introduces nonessential clauses. E.g. The team that sells the most tickets will win the contest. The cookies, which were left on the table for days, are already stale.

4. That or Which or Who? If this/that/these/those has already introduced an essential clause, you may use which to introduce the next clause, whether it is essential or nonessential. E.g. That is a problem which you must deal with by yourself. Those proposals, which we have already presented, are highly popular among the members. TIP: You can often streamline your sentence by leaving out which. E.g. That is a problem which you must deal with by yourself. Better: That is a problem you must deal with by yourself.

5. Then vs. Than Than - used to indicate degree or comparison E.g. Her speech was longer than mine. Andy is much taller than Joseph. Then - used to indicate time E.g. She then stuttered during her speech and lost the contest.

6. They’re, Their, There They’re, their, and there are homophones. They are pronounced nearly the same way but they differ in meaning. They’re – a contraction of “they are”. E.g. They’re all minors. (They are all minors.) I don’t know what they’re up to. (I don’t know what they are up to.)

7. They’re, Their, There Their – “means belonging to them”. E.g. That house is theirs. Were you able to locate their house? That’s their problem. There – has two uses: - to mean a place E.g. Please put the book there. -Used with the verb “to be” E.g. There is no more available seat.

8. Thru or Through? Through is acceptable in all forms of writing. On the other hand, thru – an informal spelling of the adjective, adverb, and preposition forms of through – is only used for informal writing. E.g. As an adjective: When will you be through with that project? As an adverb: Does this train go through New York? As a preposition: The burglar came in through the bathroom window. NOTE: One exception is in the fastfood term “drive-thru”, which is accepted. Thru is gaining ground these days due to social networking and textspeak.

9. To, Too, or Two? To - a preposition which begins a prepositional phrase or an infinitive. Too - an adverb which means “also” or “excessively”. Two - is a number. E.g. I went to a ballet. (preposition) We like to watch reality shows on TV. (infinitive) I drank too much. (meaning "excessively") I’m fond of sushi, too. (meaning "also") Eighty divided by forty is two. (number) I own two poodles. (number)

10. Toward(s), Forward(s) Although they say ‘towards’ and ‘forwards’ in Britain, no final s is used in American English. Similarly, it’s standard practice to not add a final s to forward, backward, upward, onward, downward, etc. E.g. When we encounter problems, we should pick ourselves up and go forward. The teenagers were last seen heading toward the forest.

11. Try and or Try to? Try and is colloquial for the phrase try to. E.g. Try and finish your work. Try to finish your work. (preferred) I am going to try and run 10 kilometers today. I am going to try to run 10 kilometers today. (preferred)

12. Unique or More unique? Primarily, unique means one of a kind, or existing as the sole example; therefore, something can’t be more unique than something else. E.g. This handbag is unique. This handbag is more unique than the one you have. - Incorrect

13. Until and By Until – used when the activity continues throughout the period until the time limit E.g. I’ll work on this experiment until 8:00 p.m. (used as a preposition) I’ll stay here until he has finished the exam. (used as a conjunction) By – used to set a time limit for completion E.g. You have to finish your term paper by Friday.

14. Whether/If These two words are often used interchangeably in informal writing and speech, but in formal writing, such as in technical writing, a distinction should be made between them, as the meaning can sometimes be different depending on which word you use. Use if when you have a conditional sentence Use whether when you are showing that two alternatives are possible

15. Whether/If  Examples where they are interchangeable: Sabrina didn’t know whether she would leave on Saturday. Sabrina didn’t know if she would leave on Saturday.  Example where they are not interchangeable: Sabrina didn’t know whether she would leave on Saturday or Sunday. (When if is used in the above example, it takes on a different meaning: In addition to leaving on Saturday or Sunday, she may not leave at all.)

16. That vs. Which Use that for restrictive clauses. A restrictive clause limits the possible meaning of a preceding subject. E.g. Animals that are endangered should not be consumed. (The words that are endangered restrict the kind of animals you’re talking about. Without them, the meaning of the sentence would change; you’d be saying that all animals should not be consumed, not just those that are endangered. NOTE: Commas are not needed around this phrase.)

17. That vs. Which Use which for nonrestrictive clauses. A nonrestrictive clause is something that can be omitted without changing the sentence’s meaning. E.g. Rubies, which are rare, can sometimes be more expensive than diamonds. (The words which are rare may be left out and the sentence would still make sense. NOTE: Nonrestrictive clauses are usually surrounded by, or preceded by, commas.)

18. Who or Whom? The words who and whom are both pronouns. First, to know whether to use who or whom, we need to talk about the difference between subjects and objects, because who is used when you are referring to the subject of a clause, and whom is used when you are referring to the object of a clause. TIPS: If we think about people, the subject of the sentence is the person doing something, and the object of the sentence is that which is having something done to them. E.g. Whom did you stay with? (If you stayed with Aunt Martha, you are the subject and Aunt Martha is the object. You use whom when you are referring to the object of a sentence. Use who when you are referring to the subject of a sentence.

19. Who or Whom? So, when is who used? If you were asking about the subject of the given sentence, then use who: Who slept with Aunt Martha? TIP: If it’s still difficult to determine which one to use, just remember that like whom, the pronoun him ends with “m”. Now, ask yourself if the answer to the question would be he or him. If you can answer the question being asked with “him”, then use whom. Whom did you stay with? (The answer here would be “her” – not she – and the male equivalent of that pronoun would be “him”. That’s your cue that whom should be used.)

20. Would rather Rather – used as an adverb of degree E.g. The croissant was rather tasty. (modifying an adjective) It happened rather abruptly. (modifying an adverb) Rather – also used to express preference E.g. I decided to call rather than write you. (comparing parallel structures) I would rather go to sleep now. (would rather + infinitive without ‘to’) I’d rather she left immediately. (would rather + pronoun + past tense)

21. You’re vs. Your You’re is a contraction of you are. It has no other uses, so if you can’t expand it to “you are”, then it’s wrong. E.g. You don’t know what you’re doing! (You don’t know what you are doing!) Your is the possessive form of you. E.g. Is this your purse? Yes, I think this is definitelyYou don’t know what you’re doing! yours. (It belongs to you.)