Sure! Let's go through the questions one by one.

**0. Which is closer to the meaning of the sentence 'Years ago I could run a marathon'?**
- The correct answer is: **b) I was once fit enough to run a very long way.**
This option captures the idea that the speaker had the ability or fitness to run a marathon at that time in the past.

**1. Which of these sentences is correct?**
- The sentences are:
1. I was ill, so I couldn't go to the party.
2. I was ill, so I wasn't able to go to the party.

Both sentences are correct and convey nearly the same meaning, though "couldn't" is often used in more conversational contexts while "wasn't able to" may sound slightly more formal.

The correct answer is: **c) I Both of them.**

**2. Which is closer to the meaning of the sentence 'Sarah was able to leave work early yesterday'?**
- The options are:
a) Sarah left work early yesterday.
b) Sarah had the opportunity to leave work early yesterday, but we don't know if she took it.

The phrase "was able to" suggests she had the capability or opportunity to do something, but doesn’t necessarily imply that she actually did it.

So, the correct answer is: **b) Sarah had the opportunity to leave work early yesterday, but we don't know if she took it.**

Let me know if you have any other questions!