1:a variety of +
复数形式,
谓语动词用单数:
I have a variety of books at home.
Society is made up of a variety of people.
A variety of other drying places was devised.
2:varieties of + 复数形式,谓语动词用复数
We offer over 100 different varieties of Corn Snakes.
Varieties of Lattices .
New Varieties of Food Additives, which were deliberated ......
类似这类量词都是一致的,比如a great amount of 和 great amounts of.