In a sentence, subject and verb must agree, for example, if subject is singular then verb must be singular, for instance, India is a country, here, India a singular noun and the verb used is "is" so here, there is agreement between subject and the verb.
Other examples are
Boys are running on the road. [ Boys (Plural Subject) Are ( Plural Verb)]
Below there is not agreement between subject and verb.
Girls is studying in the class room.
The above examples were very simple, here I will explain the students, bloggers
make mistakes whenever subject is little bit confusing.- Compound Subject - Some nouns come in pair and make a compound singular subject and they require a singular verb.
Examples are -
- Slow and steady wins the race.
- Bread and milk is my favorite breakfast.
- Rice and curry is the delicious.
- Pen and ink is used to write on the paper.
But many compound are treated as plural and they require plural verb.
Examples are -
Ram and Lakshman were living in a jungle.
Sources
[1] Subject/Verb Agreement Examples, Retrieved on 11-11-2017, Retrieved From, http://examples.yourdictionary.com/examples-of-subject-verb-agreement.html.
[2] 20 Rules of Subject Verb Agreement, Retrieved on 11-11-2017, Retrieved From, "http://grammar.yourdictionary.com/sentences/20-Rules-of-subject-verb-agreement.html".