In a sentence subject verb agreement is critical. You don't want a singular subject with a plural verb. There are certain rules for this, and you will need to be familiar with it before writing. If your subject verb agreement is wrong the whole sentence will sound funny. Remember if your sentence contains a compound subject and one is plural, choose a verb that agrees with the positive subject.
. For more on this see, http://grammar.ccc.commnet.edu/grammar/sv_agr.htm
