What are the roles of opposition parties in multipartism?

Though parlimentary governments differ from country to country, they function in more or less the same way. As the distinguished Canadian parliamentarian Stanley Knowles put it: ... the opposition should so conduct itself in Parliament as to persuade the people of the country that it could be an improvement on the government of the day. No one will deny that our system works best when there is a change of government at reasonable intervals. The role of an opposition party, Mr. Knowles noted, is to check and prod, but ultimately to replace the government party. http://fergionline.blogspot.com