there are thousands of people visiting our school each year.请问这个句子中的visiting为什么要加ing?to visit不行吗?

There are thousands of people in the there are thousands of o_____in the museum's collection. there are thousands of books in the college( ) There are two____students in our school.A.thousands B.thousands of C.thousand of D.thousand there are _ of visitors to Kunming. (A.tens of thousands B, about ten of thousands There are three ____ students in this school.A thousand B thousands C thousand of D thousands of There are about six __students in our school.A.thousand B.thousands of c.thousands D.thousand of There are more than eight ___students in our school.A.thousands B.thousands ofC.thousand of the D.thousand of There are （ ） trees on the hill.A.thousands of B.two thousand of C.two thousands D.thousan of There are about 200 --people in the hall A.thousand B.thousands C.thousand of D.thousands of There are about thirty()people living in the town.A.thousands B.thousand C.thousand of D.thousands of 19.There are three _____ workers in the factory.A.thousands B.thousands of C.thousand选哪个,为什么? How many students are there in your school?A Thousands B Thousand C Thousands of D Two thousandsA Thousands B Thousand C Thousands of D Two thousands 选择哪一个答案 又many又thousands of?there are many thousands of children who can not go to schoolmany 与 thousands of 不怕意思重复么? There are ______ monkeys on the Monkey Island.A.hundred of thousands of B.hundred of thousands of C.hundreds of thousand of D.hundreds of thousands of there are thousands of people standing outside the gate now.为什么不能写 are standing We are looking forward to see the player改错 In the box there are two thousands There are three__students in our school,but only one __them are girls.请问答案是什么A.thousands,thousands of B.thousands,thousand ofC.thousand,thousands of D.thousand ,thousand of