"Last and "past" are not interchangeable.
The word "last" implies finality, no more, all gone.
Right: She ate the last cookie.
Wrong: During the last month, it never rained.
Right: During the past month, it rained six times.
Which and that are not the same and are not interchangeable.
Right: The dog that ate my homework is a puppy.
Wrong: The dog which ate my homework is a puppy.
Right: The dog, which ate my homework, is a puppy.
Think about each sentence and how they differ.
Which should always be preceded by a comma.
Since and because are not the same and are not interchangeable.
Many of us misuse "since" in our writing and when we speak.
Use "since" when there is a time element.
Use "because" when something is conditional.
Right: Since Sunday, it has snowed 4 inches.
Wrong: Because Sunday, it has snowed 4 inches.
Right: Because it's dark outside, we'll use flashlights.
Wrong: Since it's dark outside, we'll use flashlights.
One of a writer's chief goals should be write with such clarity that a reader does not have to reread a sentence to grasp its meaning. The writer has failed if the reader must read a sentence twice.
One of my clients repeatedly wrote sentences of 50, 60, and even more than 70 words. One sentence contained 115 words, 15 commas, and six semicolons. That's asking a lot of the reader.
My suggestion for improving such wordiness is to read newspaper articles, magazine articles, books, and scholarly documents -- then judge the clarity of the work, and count the numbers of words in sentences that are easy to understand. I think you'll agree that fewer words usually translates to better writing.
That said, I must add this caveat: A novel I just finished contained many long sentences. And the author had the skills to make long sentences work. One sentence was 215 words, had two dashes, 15 commas, two parentheses, three semicolons, and one colon. It worked, and I did not have to reread it to understand it!
That's correct. In this case, aid is money.
It's not financial "aide." An aide is an assistant.
These words are easy to misuse.
Predominant: It's an adjective. One of its definitions is "most frequent."
Predominate: It's a verb. One of its definitions is "to be dominant in amount."
Use toward in all cases.
You'll find towards in the dictionary, but I urge that you always use toward. Toward passes muster; towards does not.
Example: The teacher told the students to "do" the math problems tonight because the assignment is "due" tomorrow.
See the difference: do and due.
It's one of those oversights that's easy to make.