Apply the given rules of subj-verb agreement to proofread the given sentences.

Question

1- The army need new supplies. 

2- The pack of wolves work together to find food and shelter.

3- Genetics are often used to reinforce existing prejudices.

4- Millions of people watched the high-speed chase and most was mesmerized by the event.

5- All of the cake are missing its frosting.

Answer 1

1- The army need new supplies. 

3- Genetics are often used to reinforce existing prejudices.

4- Millions of people watched the high-speed chase and most was mesmerized by the event.

5- All of the cake are missing its frosting.

Subjects and Verbs must be in agreement.

If you have a singular subject, you must have a singular pronoun.

So,

1. The army needs new supplies is correct. The army is considered one unit and a singular noun so it needs a singular subject.
2. This one is tricky the object of the preposition of could confuse some readers. 2- The pack of wolves works together to find food and shelter. The subject is pack, not wolves. Therefore you need a singular noun. Pack is singular.