Answer:
1 - Because of lack of time, we didn't manage to finish the work.
2 - When my sister is angry, her face will turn red.
3 - Because chocolate has a low-melting point, it melts very easily.
4 - Since I'll be working late, I'll eat downtown.
5 - Normally they wouldn't be too concerned about it, but this just crossed the line.
6 - If you pay your bills on time, you can have a good credit score.
7 - He will drink some water because he is thirsty.
8 - Give us a call when you get back from your trip.
9 - You need to remain calm even if everyone else panics.
10 - I won't allow you to see that movie even though you are old enough to go.
11 - We can get some new clothes as long as the store is open late.
12 - The fireworks show will start after the sun goes down.