1. The correct form is "prevent someone from doing."
2. The word that means to create something which has never existed before is "invent."
3. The word we use with "I" when making offers and suggestions in the question form is "shall."
4. The form that is more informal is "will."
5. The two negative forms of "He is" are "He is not" and "He isn't."

The correct form is "prevent someone from doing."

The word "invent" means to create something which has never existed before.

The word "shall" is used with "I" when making offers and suggestions in the question form.

"Will" is more informal than "be going to."

There are two negative forms of "he is": "he isn't" and "he's not."