CHRONIC and ACUTE

These are medical words: chronic means a long-lasting condition and acute means one which is short-lived and flares up suddenly: chronic rheumatism but an acute attack of 'flu.

Chronic has spread into general usage as in chronic disrepair and in colloquial speech it can mean very bad as in: the book was chronic, though this now seems somewhat outdated.
Acute is also used outside medicine as in: I was acutely aware or: He felt an acute sense of guilt where it means sharply or piercing..

i before e

This is a commonly quoted rule but a vital part of it is often omitted. It should read:
i before e except after c but only when the ie sound says ee.
e.g. chief, field but deceive, receive
Exceptions are: seize, protein

When the ie sound does not say ee, the e can go before the i: weight, height.

This rule has one very useful application: Internet fraudsters can rarely spell receive correctly!

Outside

The expression is outside the shop never outside of the shop.

The APOSTROPHE of possession

This is the apostrophe that shows that someone/something owns something. You add it to a noun which otherwise does not indicate ownership: boy for example.  You do not add it to a word which already suggests ownership: hers.

There is one technique for knowing where to put it that covers ninety-nine per cent of cases and you can avoid the others by re-wording your sentence.

Turn the phrase around so that it reads: the ... of the ...  the books of the boy. Add the apostrophe and s at the end of this new phrase. Then turn the phrase back again: The boy's books
Similarly: the books of the boys. Add the apostrophe and s at the end and turn it back: the boys' books.

There is a knottier problem with the name of someone like Keats which ends in an s. Best to simply add it to the name: Keats' or leave your phrase as the poetry of Keats. Just be sure you do not put it between the t and the s or else you are calling him Keat!

THROUGH, THOROUGH and THREW

Through is a preposition which can make a phrase with a noun: through the window.
Thorough means in detail, complete, with care. His work was always thorough.

A good way to remember is that thorough is a longer word and it suggests taking a long time over something.

Threw is the past tense of throw. She threw the jewel across the room.  Remember this sentence and the two ew syllables.

UNINTERESTED and DISINTERESTED

Uninterested means not interested.  The audience was uninterested in his boring speech.
Disinterested means impartial or not taking sides. The umpire remained disinterested despite the argument between the players over his decision. This means that the umpire did not side with anyone but still would have been interested in the argument.

Recently this precise use has become confused with uninterested but it is better in written or formal English to keep the meanings separate.