Yet

[jack]

What do these mean?
1. I have yet to make a call. (What does 'yet' mean? I have looked that word up but I don't understand how to use it.)
2. I have to make a call.

[Mister Micawber]

(1) is a somewhat formal use of 'yet' nowadays, Jack. The sentence means 'I have still not phoned/visited'.

(2) is quite different. It means 'I must phone/visit'.

[jack]

Thanks.