a variety of主谓一致

avarietyof+复数名词”作主语时，是用单数还是用复数？ “a variety of+复数名词”作主语时，是用单数还是用复数？请帮助找一些权威用法。一、“a variety of+复数名词”作主语，谓语用复数的实例A variety of treatment methodsexist.有各种各样的治疗方法。引自柯林斯高级英语用法词典(Collins Cobuild English Usage)（上海外语教育出版社）第971页Agreat variety of animalssurvivethere.那儿仍然生存着各种各样的动物。引自柯林斯高级英语用法词典(Collins Cobuild English Usage)（上海外语教育出版社）第971页Therearea variety of apples in the shop.商店里有各种各样的苹果。引自新时代英语惯用法词典（外文出版社）variety词条Therearea wide variety of people on the earth.地球上有各种各样的人。引自外研社建宏英汉多功能词典（外研社）variety词条二、“a variety of+复数名词”作主语，谓语用单数的实例Thereisa wide variety of flowers.有很多种类的花。引自张道真的初级英语词典（外研社）variety词条Theresa large variety of goods in the shops.商店里有各式各样的商品。引自张道真英语用法goods词条wine bar: place where a variety of winesissold and drunk, sometimes with food (供应各种果酒的)酒吧，酒馆(有时供应佐酒食物)引自牛津高阶英汉双解词典(Oxford Advanced Learners Dictionary of Current English) (第四版) win词条Therewasa considerable variety of opinions.这里有各种各样的看法。引自新时代英语惯用法词典（外文出版社）variety词条三、“a variety of+复数名词”作主语，谓语用单数/复数的实例A variety of reasonswereorwas offered for the long delay.引自钱伯斯基础英语词典(Chambers Essential English Dictionary)（外研社）variety词条Thereareor Thereis a variety of excellent schools in the area.引自钱伯斯基础英语词典(Chambers Essential English Dictionary)（外研社）variety词条There is a wide variety of patterns to choose from.有种类繁多的图案可供选择。 （牛津高阶英汉双解词典 第七版）There is a wide variety of new music to be dicovered in every co