1. Research during the past several decades on the nature of language and the processes that produce and make it understandable has revealed great complexity instead of underlying simplicity.
(A) that produce and make it understandable has revealed great complexity instead of underlying simplicity
(B) of producing and understanding it have revealed not underlying simplicity but great complexity
(C) by which it is produced and understood has revealed not underlying simplicity but great complexity
(D) by which it is produced and understood have revealed great complexity rather than underlying simplicity（A）
(E) by which one produces and understands it have revealed great complexity instead of underlying simplicity
it 是指代什么？
我认为 it 指代的是 language. 可以从两个方面判断，第一，从结构 on the nature of language and the processes 看，the nature 和 the processes 是并列的关系；第二，从结构 the processes that produce and make it understandable 看，produce 和 make 是并列的关系，既然produce 肯定是与 language关联的，那make 也应该是与 language关联的。此外，从意思上看，make it understandable， 也只能是language, 而不是 the nature of language。（语言是可理解的，而不是语言的本质）
