Subject/verb agreement

Subject/verb agreement is a grammar point that poses some difficulties to English students of all levels. On the surface, it is quite easy to grasp the fact that a singular subject demands a singular verb, and a plural subject needs a plural verbs, as in these examples:

The boy is crying (singular subject / singular verb)
The boys are crying (plural subject /plural verb)

Unilearning, an Australian webpage designed for overseas foreign students, has created an online activity where students are tested on the subject/object concord.

The activity is suitable for intermediate students.

If you are interested in this topic, A clil to climb published two posts about it recently:

How much is... or how much are? and there is or there are?