Choose the word (or words) that make best sense to fill in the gap.In the British countryside you can usually tell when it's going to start raining, if you see a ... ... of cows all lying down on the grass.

We often need to discuss quantities and the words and terms associated with them ('how much' of something), so at this stage in your English learning you need to know 'Enough, but not too much' about this important aspect of everyday conversation.