a lot - The proper form is two words, not alot.
agree on - must be followed by the -ing form of a verb.
an instance of - is different in meaning from an example of. An example is one of a number of things while an instance is an example that proves or illustrates. People may be examples but never instances.
as vs. than - The words are not interchangeable. Use as for comparisons of similarity or equality and than for comparisons of degree or difference. Always use than with the comparative (-er) form of an adjective.
as good as or better than - is a cliche and should be avoided. Do not telescope a comparison of similarity - as with a comparison of degree - than. A better construction is to break the juxtaposition up into separate thoughts.
as ... as - is a grammatical way of expressing similarity: he is as tall as his sister.
such ... as - is grammatical when both words are used as prepositions in a comparison: such men as he. Avoid as such when meaning in principle.
based on - The phrasal verb based on is grammatical and can be used either actively or passively.
The style of her cooking is based on Southern cuisine.
She bases her thinking on sound logic.
depends on whether - The construction is generally accepted and is certainly preferable to depends on if.
His fate depends on whether the governor calls back in time.
different from vs. different than (differ from) - Although strict grammarians say that from is the correct word to use after different, many authorities believe that than may be used in order to avoid elaborate constructions. In contrast, the authorities agree that from is the correct word when used with differ.
He is a different man than he was in 1985. Compare to: He is a different man from the man that he was in 1985.
Identical with/to - Identical may be used with either preposition without changing the intended meaning.
no less a ... than - The expression is an accepted idiom meaning great or not less impressive.
not only/but also - Not only is always followed by but also in a sentence.
The subways in summer are not only hot, but also humid.
regard as - The verb regard may be used with as and either an adjective or a noun.
We regard George's ranting as silly. The tribe regards shaking hands as taboo.
Do not use regard with an infinitive or being: He is regarded to be an expert; He is regarded as being an expert.
regardless - The word is correct. Irregardless is non-standard usage.
So ... as - The comparative construction may only be used in questions and negative statements. Otherwise, use as ... as.
Your house is not so large as mine.
So ... - Avoid the use of the appealing so as an intensifier. The weather is so delightful. Very would be a better choice. Similarly, when using so with a part participle, consider using much or well to qualify.
The car was so much damaged that it was not drivable.
Mary is so well suited to be an attorney.
Aggravate/annoy - To aggravate is to make a situation worse. To annoy is to irritate. In formal English, people cannot be aggravated, only annoyed.
When the Chairman of the Federal Reserve lowered interest rates, he aggravated the flailing economy and annoyed many Wall Street bankers.
Ago/since - Ago carries a thought from the present to the past. Since carries a thought from the past to the present.
It was twenty years ago that I first heard that song.
It has been twenty years since I first heard that song.
Among/between - Use between when comparing two items and among when comparing three or more
I was torn between studying finance and studying marketing.
After I was accepted into all three MBA programs, I had to choose among Harvard, Wharton and Columbia.
Amount/number - Use amount when referring to an uncountable noun and number when referring to a countable word.
There is a large amount of water in the ocean.
There are a large number of fish in the ocean.
Fewer/less - Use fewer when referring to a countable noun and less when referring to an uncountable noun. The usage of fewer/less is similar to amount/number.
The supermarket express lane is open to customers with ten items or fewer.
There is less rudeness at Dean and Deluca than at Fairway.
Good/well - When used as adjectives, good refers to morality or quality and well refers to health. However, only well can be used as adverb and good is always an adjective.
I feel good about my work.
I feel well.
I am well.
I'm doing well.
It is good to hear that you feel well today.
Imply/infer - To imply is to express a thought indirectly. To infer is to derive a conclusion indirectly.
While the politician never implied that he would raise taxes, the audience inferred that he would soon do so.
Like/as - Use like before a noun, or pronoun. Use as before a clause, adverb or prepositional phrase. Like is generally used as a preposition in such a context. As is generally used as an adverb while sometimes serving as a preposition with the meaning of ``in the capacity of''.
My mother's cheesecake tastes like glue.
I love frozen pizza because there is no other snack like it.
My mother's cheesecake tastes great, as a mother's cheesecake should.
There are times, as now, that learning grammar becomes important.
He golfed well again, as in the tournament last year.
He served as Captain in the navy.
Less than/under - Less than is the correct expression when making a comparison of number or amount. Under is limited to describing spatial relationships.
I will host the party if the guest list is less than fifty people.
More than/over - More than is the correct expression when making a comparison of number or amount. Over is limited to describing spatial relationships.
We processed more than 1,000 applications in one hour.