Great as Newton was, many of his ideas_____today and are being modified by the work of scientists of our time.

A．are to challenge

B．have challenged

C．are challenging

D．have been challenged

免疫荧光抗体技术间接法是将荧光素标记在（）

A.补体

B.抗补体抗体

C.抗免疫球蛋白抗体

D.特异性抗原

E.特异性抗体