Yes, "two-and-a-half" should be hyphenated when used as a compound adjective before a noun, such as in "two-and-a-half years." However, when it stands alone or follows the noun, it is typically written as "two and a half."
It should be hyphenated.
It should be hyphenated if used as a noun clause, but not if used as an adjective
Yes, "half-page ad" should be hyphenated to show that "half" and "page" are acting together as a compound adjective to describe "ad."
No, "half sister" is not hyphenated. It is considered a compound noun and is typically written as two separate words. However, "half-sister" is hyphenated when used as a compound adjective before a noun, such as "my half-sister's birthday."
It should be hyphenated.
Self-made should be hyphenated.
Pre construction - two words not hyphenated.
No, "two thirds" should not be hyphenated. It is a compound adjective that functions as a single unit modifying a noun.
No, the phrase "hour and a half" is not hyphenated when used in a sentence. It should be written as three separate words. However, when used as an adjective before a noun, it can be hyphenated, like in "an hour-and-a-half meeting."
Underdeveloped should be written as one word, not two words or hyphenated. I hope this answered your question. :)
No, "by and large" should not be hyphenated. It is an idiomatic expression meaning "generally" or "for the most part." When using it in writing, it should appear as two separate words.
Roller-skate, as a verb, should be hyphenated. Roller skate, as a noun, is not.