1. This book was most helpful for my homework.

2. This book was the most helpful for my homework.
(Which one is grammatical? Do we have to use 'the' or not in this case?)

Q: How do we pronounce 'helpful'?
(It's a little difficult to pronounce...Thank you for your help.)

#1 means this: This book was very helpful for my homework.

#2 means this: Of all the books, this book was the most helpful ...

Both are grammatical, but they are not identical in meaning.

Yes, "helpful" is difficult ... it's because of the l and p and f sounds all together between the two vowels.

http://dictionary.reference.com/browse/helpful?s=t
See the little icon for a speaker, right next to helpĀ·ful just above the definition? Click on it, and you'll hear a man pronounce the word.

Both sentences are grammatically correct, but they have slightly different meanings. Let's break it down:

1. "This book was most helpful for my homework."
In this sentence, "most" is an adverb modifying the adjective "helpful." It means that the book was extremely helpful for your homework compared to other books or resources you may have used. Here, "the" is not used.

2. "This book was the most helpful for my homework."
In this sentence, "the" is used before "most." This implies that you are comparing this book to other books or resources you may have used, and this particular book was the most helpful one. It emphasizes that this specific book stands out as the most helpful option.

As for the pronunciation of "helpful," here is a guide:

- The word starts with the "heh" sound, similar to the letter "h."
- The "ehl" sound is pronounced like the "el" in "elephant."
- The final "ful" sound rhymes with "full" or "pull."

Putting it all together, you would pronounce "helpful" as "HEHLP-fuhl."