成千上万的儿童用英文怎么说

"Thousands of children" 用英语表达为 "thousands of children"。这是一个固定短语，其中 "thousands" 是数词，表示 "成千"， "of" 是介词，表示所有关系，"children" 是名词，表示 "儿童"。

例句:

Thousands of children are in need of education. (成千上万的儿童需要教育。)
The charity provided aid to thousands of children in the disaster-stricken area. (这个慈善机构向灾区的成千上万儿童提供了援助。)