choice of prepositions

[hela]

Dear teachers,

Would you please tell me if the preposions in blue could be used in the following sentences?

1- What was the happiest day of / in (?) your life?

2- As you know, it's Burt's birthday (on ?) next Friday.

3- (For ?) How long will you be here?

4- How long will you be here (For ?) ?

5- (For ?) How long have you known him?

Many thanks,
Hela

[Rusty]

Dear teachers,

Would you please tell me if the preposions in blue could be used in the following sentences?

1- What was the happiest day of / in (?) your life?

2- As you know, it's Burt's birthday (on ?) next Friday.

3- (For ?) How long will you be here?

4- How long will you be here (For ?) ?

5- (For ?) How long have you known him?

Many thanks,
Hela
1- What was the happiest day of / in (?) your life? (Both OK. Of is more common).

2- As you know, it's Burt's birthday (on ?) next Friday. (Use either on or next, but not both).

3- (For ?) How long will you be here? (OK).

4- How long will you be here (For ?) ? (OK).

5- (For ?) How long have you known him? (OK).

[Beery]

In "How long will you be here for?" isn't "for" a hanging preposition?

[Rusty]

In "How long will you be here for?" isn't "for" a hanging preposition?
Yes, it is. Hanging prepositions should be avoided in formal writing. They are commonly heard in spoken English and are (in my opinion) borderline/debatably acceptable.

[danmahaffey]

I think for is like at in the sentence, Where is the library at?

This is not so much a hanging, or better, a stranded preposition, but a redundant preposition, since the adverbs how and where already include the senses of for and at, respectively. For should be deleted.

Stranded prepositions, and prepositions that are part of phrasal verbs often occur at ends of clauses and sentences for natural grammatical reasons. They should have impunity, and shouldn't be assailed merely for that reason alone. Redundant prepositions and bad diction should always be corrected.

Here is a perfect stranded preposition: What are you thinking of?

Here is a perfect phrasal verb: We were in the neighborhood and thought we'd stop in.

:)