lt is-- to work out this proplem .you needn't go

选C
lt is_easy enough_ to work out this proplem .you needn't go to the teacher
A.enough easy
B.easily enough
C.easy enough
D.very easily
意为：这题简单到（我们）足可以做出来,你不必去问老师
adj+enough to do；足以（做）…
例句：
She's old enough to have the freedom to do as she likes
她已成年了,有权做她喜欢做的事.（她已经大到有自由做喜欢的事）
Would you be kind enough to do it for me?
劳驾你帮我做这件事好吗?（你有足够的善意帮我做这件事吗?）
再问： 为什么不能选B
再问： 为什么不能选B
再答： easily是副词。
lt is_easy enough_ to work out this proplem，
相当于：to work out this proplem is easy。
即it=to work out this proplem。
lt is easy 就是一个完整的句子，可理解为这件事很容易，
但很难讲lt is easily，因为副词通常不直接修饰名词。