Final answer:
The two plural or possessive errors in the given sentences are using 'students' instead of 'students'' to show possession, and misusing the possessive form of 'university'.
Step-by-step explanation:
The two plural or possessive errors in the given sentences are:
- Using 'students' instead of 'students'' to show possession:
- Many students' ability to pay for college is limited.
- Misusing the possessive form of 'university':
- However, universities' financial aid packages can help offset some of the necessary expenses.