2. ... to the questions, he wouldn't have got all the answers wrong.
3. ... got all the answers wrong, the other kids wouldn't have laughed at him.
4. .. have felt really miserable if the other kids hadn't laughed at him.
5. If he hadn't felt really miserable, he wouldn't have eaten a huge lunch.
6. If he hadn't eaten a huge lunch, he wouldn't have been sick later on.