The phrase "king of grapes" should not be capitalized unless it is part of a title or a proper noun. In general usage, it remains lowercase. However, if you're referring to a specific brand or wine known as the "King of Grapes," then it would be capitalized. Always consider the context to determine proper capitalization.
Have should be capitalized if it is the beginning of a sentence. Summer should not be capitalized.
He ate green grapes.
The phrase "Martin Luther King Day" is correctly capitalized. Martin Luther King is a name so is automatically capitalized. Since it is a specific day, a holiday to be exact, day is also capitalized.
It should only be capitalized if it forms part of a title.
As an abbreviation it should be capitalized.
Yes it should be capitalized.
Yes it should always be capitalized.
Yes it should be capitalized.
No it should not be capitalized.
The first 'c' should be capitalized.
Yes, it should be capitalized.
No. It should not be capitalized.