--Did you hear something?--No. I ______ but I ______ anything at all.
If you_____this experiment you will understand the theory better.
I don’t like to be interrupted if I_____.
I wonder if he_____us, and I think if he_____us we’ll be able to complete the task ahead of time.
You won’t succeed_____harder.
_____ weather permits, we’ll have an outing.