9. If Sam (train) harder, he could have got first place in the track event. 10. Milk goes off if you ........................................ (not/keep) it in the fridge.

Solution:

Fill in the blanks with the correct form of the verbs in brackets.

1. If Sam trained harder, he could have got first place in the track event.
2. Milk goes off if you do not keep (or don't keep) it in the fridge.

Answer: trained; do not keep (or don't keep).