English plurals: Tricky endings

No language can thrive without having a way for its speakers to express things in the plural; for example, two desserts are always better than one. As you know, most English nouns form their plurals by adding s or es. But a simple rule with no exceptions would be boring, don't you think? Test your knowledge by choosing the correct plurals for the words below.

1. The plural of person is Placeholder for the answer.
2. The plural of appendix is Placeholder for the answer.
3. The plural of ox is Placeholder for the answer.
4. The plural of corpus is Placeholder for the answer.
5. The plural of offspring is Placeholder for the answer.
6. The plural of vertebra is Placeholder for the answer.
7. The plural of bacterium is Placeholder for the answer.