I learnt at school that you use the present tense in an adverb clause even if you mention the future, but I often encounter adverb clauses with the present-perfect tense. I would like to know the difference between the two.
- 1-1. I'm going to Rome when I have finished my Italian lessons.
- 1-2. I'll go shopping if it has stopped raining by this afternoon.
- 1-3. Don't drive a car when you haven't had enough sleep.
These three sentences are from my English textbook at school. What is the difference between the sentences above and below?
- 2-1. I'm going to Rome when I finish my Italian lessons.
- 2-2. I'll go shopping if it stops raining by this afternoon.
- 2-3. Don't drive a car when you don't have enough sleep.
My textbook doesn't describe the difference. I'd appreciate it if you could help.