English grammar rule Mass agreement
In any sentence, singular subjects need singular verbs, and plural subjects need plural verbs. Sometimes, it is difficult to keep track of which subjects and verbs must agree. In that situation, ask yourself which subject is “doing” which verb. Keep in mind that sometimes there represents the subject, such as There are many people watching the movie or There is a coat by the door. In this case, the verb must agree with the subject of the clause, usually the word after the verb.
Examples of 'Mass agreement' rule
Incorrect I hope you travels well. Correct I hope you travel well. Incorrect That lecture, including the part where the speaker tried to be funny, are pathetic. Correct That lecture, including the part where the speaker tried to be funny, is pathetic