You would need to introduce a list.
For example you could have: My shopping list contains of; milk, bread, and yogurt.
Another purpose is to separate clauses.
Explanation: It is important not to over-rehearse a talk or speech.
Answer:
It is a pun.
Explanation:
This is because it is a figure of speech that exploits a word's meaning in this case that the book was impossible to put down.