---How often do you turn to the dictionary when you are reading an English novel?

---Well, ___. I will look the word up if it affects my understanding.

A．seldom

B．very often

C．it depends

D．if possible

下列关于人类基因组计划研究的意义的叙述不正确的是[ ]

A．有利于诊断和治疗各种疾病

B．有利于了解人类的起源

C．有利于了解基因表达的调控机制

D．有利于了解传染病的发病机理