Would you explain and correct for me :

1) sometime = at some time
  • I will meet him sometime around 8:00 this evening.

2) some time = for some period of time
  • I will stay with him some time around one hour.
(Actually, I want to say I will stay with him around one hour time, but I want to try to make a sentence with "some time")


3) What is the usage guideline for "Owing to / due to"?

a) I was not able to join the party due to the flight delay from China.
b) Owing to the fact that the flight was late from China, I was not able
to join the party.
c) Owing to the flight delay from China, I was not able to join the party.

Thanks