Number refers to singular (one) or plural (more than one). Number is not generally an issue if you’re writing in the first person (that is, if your subject is I or we) or the second person (you), because the verbs use the simple base form, with no ending: I throw. You catch. We play.

Nearly all the academic writing you do, however, will be in the third person, and here number matters a great deal. The verb for a singular third-person subject needs an -s or -es ending: She throws. He catches. The verb for a plural third-person subject requires the base form, with no ending: They play.

An important exception to this pattern is the highly irregular verb be: I am. You are. He/she is. We are. You are. They are.

My self-reliant and hardworking, and so My both

thrifty. influenced by their values.

These rules might seem fairly straightforward. Once you start writing real sentences about real topics, however, you’ll find that number can cause trouble in a variety of situations.