问题补充：
Such a problem is＿＿＿＿difficult for a primary school student ＿＿＿.
A. so； to work
B. very too； to work out
C. rather too； to work out
D. quite too； to answer
答案：
A. so； to work
B. very too； to work out
(答案→)C. rather too； to work out
D. quite too； to answer
解析：这是一个too... to... 的句型，首先排除A。very不能修饰too, 而rather可以。其次，work out常与problem搭配，而answer多与question搭配。
