Choose the correct item

1. [Unless|When] George sees a dog in the street, he freezes because he's terribly afraid of them.
2. Helen wouldn't have been so upset
   [if|unless] you had told her the whole truth.
3. We can go to the new Thai restaurant tonight,
   [if|unless] you'd rather stay in.
4. [When|Unless] I miss the bus, I'm late for school.
5. Would you scream
   [when|if] a big spider crawled up your leg?
6. Jane won't be able to improve in painting
   [when|if] she doesn't practise more often.