RON:the principal objection here is that the meaning is incorrect/unclear: for instance, a 'two-year low level' could mean that it hit a low level and then stayed there for two years.
consider other uses of the adjective "two-year":
a two-year lease is a lease that LASTS for two years.
a two-year recession is a recession that LASTS for two years.
a two-year marriage ... etc. etc.
E中修饰differences的是形容词significant,这个词的意思是“意义重大的”,而D中的significantly是副词,意思是“程度深地”。在这道题目中,意思上肯定是”程度上十分大的不同“,所以E是不对的。
little of +单数