—The lights in the classroom are still on. Do you know______.

—To revise for the coming exams.

A．what they stay up late for

B．why they stay out late

C．when will they stop studying

D．how they work on their lessons

早孕习惯性流产者应首先进行的遗传检查是（）。

A.针对染色体数目结构异常的核型分析

B.SNP分析

C.某些酶的活性检查

D.病毒感染的基因诊断

E.RELP分析法