“How many days are there in a week?”这句话为什么要加“are there”?

how many days are there in this How many days are there in December? 英语翻译How many days are there in a year How many days make a year How many days are there in Jnly?怎嘛答 They are ? 回答下列句子 How many months are there?How many days are there in a week? how many days are there in a week?怎么回答 How many month days there are in a 造句 how many days are there in january的回答 How many days are there in a week? How many days there are in a week造句 How many days there are in a week 造句 How many days are there in a year How many days are there in a leap year?回答 How many days are there in July?回答此问题. How many days are there in may?回答什么? How many hours are there in 7 days How many days are there in a week What are they?怎么回答 there,days,31,are,in,May 连词成句birthdays,many,are,how,February,there,in