Was the volleyball thrown on the playground by the boys
先转化为被动语态
之后再转化为疑问句
这样比较好理解!按以下4步!
1.Did the boys throw the volleyball on the playgruond?
2.The boys thrown the volleyball on the playgruond.
3.The volleyball was thrown on the playgruond by the boys.
4.Was the volleyball thrown on the playgruond by the boys.