There is an interesting discussion going on at the Language Log today concerning verb agreement. As examples Geoffrey Pullum (who is a professor of linguistics at Edinburgh University) gives the following:
We can't leave the garden unwatered during what is usually the hottest sixty days of the year
We can't leave the garden unwatered during what are usually the hottest sixty days of the year
Professor Pullum thinks that both versions are correct, although he concedes that there is a subtle difference in the viewpoint of each sentence. The decision whether to use a singular or plural verb is often more a matter of judgement than one of strict rules matching singular verb with singular noun and plural verb with plural noun. Here are some headlines from Google News page today:
England have no defence
New Zealand set the benchmark
Scotland have high hopes after Auld Enemy is pitched in path
A plural verb is used in these phrases because, although the countries are technically grammatically singular, rugby teams are meant, and a team consists of several people. The same thing happens with other singular nouns which denote a group of people eg government, company, committee and family. The examples below all come from the British National Corpus:
The government have introduced some initiatives ...
... by 1859 the company were no longer operating from there
"The committee are absolutely appalled," he said
... it will reassure him that his family love him and are there to help him ...
South Africa faces Wales, New Zealand meets France