Good luck on that.

[diamondcutter]

A: Hey, how's it going?
B: Oh, all right. I'm trying to make friends.
A: Oh, that’s great! Everyone needs friends.
B: ( 76)?
A: Yes. I think you should talk more often with the people who you want as friends!
B: Okay, thanks for your advice. I have one more question though.
A: Go ahead please.( 77).
B:Should I try to get their phone numbers?
A: ( 78). Friends need to communicate with each other.
B: Then I won't be shy to ask for their phone numbers. ( 79)?
A: You can make friends with any kind of person. I became a friend to an old man and to a young kid.
B:Wow, that's amazing.I didn't know making friends would be easy. ( 80).
A: Good luck on that. Goodbye.
B: Goodbye.

Source: http://m.1010jiajiao.com/czyy/shiti_id_0b3ff8b6f25ec0bd45bc371cbc41f1ef?ivk_sa=1024320u

This is a test question. Students have to write proper sentences to complete the dialogue. I have no questions about the answers but this sentence: Good luck on that. It looks odd to me. Is it correct? What about replacing it with the following sentence?
Good luck to you!

 

[emsr2d2]

This is a test question. Students have to write proper sentences to complete the dialogue. I have no questions about the answers but this the sentence no colon here "Good luck on that" no full stop here It looks odd to me. Is it correct? What about replacing it with the following sentence?
Good luck to you!

You're right that it's odd. I'd just say "Good luck" but "Good luck to you" is OK too.

We use "Good luck with that" but it's frequently used in a sarcastic way when the speaker thinks that the other person has little/no chance of success.

Emsr2d2: I'm going to spend the afternoon trying to explain to learners why they shouldn't try to start sentences with "and", "but" and "so".
Other teachers here: Good luck with that!

 

[Rover_KE]

I'm going to spend the afternoon trying to explain to learners why they shouldn't try to start sentences with "and", "but" and "so".

I've just this minute done that here, where 'But' means 'However'.

 

[emsr2d2]

I didn't say everyone should avoid it. I generally tell learners to avoid it until they're absolutely sure they know what they're doing!