I looked up 5 grammar rules today that had been fuzzy in my head. Here’s what I learnt:
Question: Is it Tim Ferriss’ podcast or Tim Ferriss’s podcast.
Answer: Both are correct. Here’s an article that gives the details: Link
Question: Raise vs Rise
Answer: The boy raises his hand (he did it; it didn’t happen on its own accord) whereas the sun rises in the east (the sun does so by itself; no one had to ‘raise’ it). Link
Question: Is it what colour or which colour?
Answer: Both are correct. BUT, if it was a choice between a limited number of choices, you use which. For eg., it is: Red or green – which do you prefer?. Link
Question: Think of vs think about something
Answer: What did you think of John – your opinion of John
What did you think about John – what were your thoughts concerning John (more generic). Link
Question: That vs Which
Answer: The book, which is on the shelf, has a red cover. This means that the book has a red cover and happens to be on the shelf.
The book that is on the shelf has a red cover. This means that there are many books but the one on the shelf has a red cover. Link