Why should we not use a preposition here?

[Pavan]

English Language Tests, Intermediate level

ESL/EFL Test #203 "Prepositions of Time and Date (1)", question 3

I don't know what time they'll be back ......... this evening, if at all. It all depends on the road conditions today.

(a) for
(b) in
(c) (none)

English Language Tests, Intermediate level

ESL/EFL Test #203 "Prepositions of Time and Date (1)", answer 3

I don't know what time they'll be back this evening, if at all. It all depends on the road conditions today.

Correct answer: (c) (none)

Your answer was: incorrect
I don't know what time they'll be back in this evening, if at all. It all depends on the road conditions today.
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Why can't we write like this:
I don't know what time they'll be back in this evening, if at all. It all depends on the road conditions today.

why should we not use a preposition here.

Thanks,

Pavan

[Yankee]

Hi Pavan

You can say in the morning, in the afternoon, in the evening.

However, when you use the word this, then you cannot use the word in:
We're going to a party this evening.

Amy
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"Nearly all men can stand adversity, but if you want to test a man's character, give him power." ~ Abraham Lincoln

[Mujahidkhan]

can we use at with home as a preposition

[Kissy]

"At home" would be considered correct if used. When you add "at home" to the sentence in that spot, you are specifying where "back" is ("they'll be back" (where?) "at home").

Otherwise, where "back" is could be anywhere, which is why it is inappropriate for you to use the word "in". Using the word "in" means you are assuming that the sentence means "in the house, in the hotel, etc" when the person in question could be coming back to a party outdoors, a concert, etc.

Now, if this sentence was in context--as in, you are writing an essay, story, etc.--with a paragraph concerning someone not being home or whatever, it would be perfectly fine English. Rules change anyway when writing dialog within a story, essay, etc. Just understand that with a grammar or English test you cannot assume anything.