While collective nouns, which refer to groups of people, animals or things are usually singular, some of them can be used in the singular or plural. If the writer wants to focus on the group, then he will use the singular form. But if he wants to focus on the members of the group, he will use the plural forum.
The jury were unable to reach a verdict.
In the above, the author by using the plural verb were, is focusing on the individual members of the jury. If he wished to focus on the jury as a group, he would say,
The Jury locks itself up for the duration of the trial, to avoid being influenced by television coverage of the criminal proceedings.
Likewise the other collective nouns such as government, teams, people, audience can be used with singular or plural verbs depending on whether you want to focus on the members of the group or the group itself.
A list of nouns that can be singular or plural depending on the context. This usually happens when the collective noun refers to a group consisting of individual members.
In British English the collective nouns can be singular or plural. However in American English, they are always singular except in peculiar circumstances.
In the SAT, the above list of words are always singular unless the context forces the reader to look at the individual members, in which case they are plural.