新一代智能书包多少钱:there are a series of 还是is,还有there are a wide variety of还是 is ?谢谢

there are a series of 还是is,还有there are a wide variety of还是 is ?谢谢 ______ _____hours are there in a day? a series of books 后面加is 还是 are？ 3.There are ______months in a bour. 4.There are ______ hours in a day. How many feet are there in a yard? There are many kinds of a ____in the big zoo. There are one hundred cents in a dollar. Google难题：How many Pings are there in a Dunam? how many pence are there in a pound? how many inches are there in a foot