a great deal of research has been done into the possible causes of cancer.何意?

a great deal of a great deal of造句 A great deal of还是A large deal of a good deal of等于a great deal a great deal of=a great number of吗 a great deal of 怎么用?举例说明 a great deal of +可数还是不可数? make a great deal of difference是什么意思 a great deal of意思及用法 a great deal of+可数吗? have a great deal of trouble (in) a great deal of和a great numberof的区别 a great deal of 和 a great many的区别 a great many 和a great many of 的区别 a great deal 和a great deal of 的区别 a great deal of,a great deal,a great number of,the number of有什么区别? a great deal of与a great deal有什么区别 a great deal of和a large number of区别 great deal of和a large amount of的用法?