Question

The light will be thrown ______ the cause of cancer by research that is now in progress

1. A.
   to
2. B.
   upon
3. C.
   in
4. D.
   for

Answer 1

B
考查介词的用法。句意“正在进行的研究将对癌症的起因进行解释。”throw light on/upon sth.“解释，阐明”。故选B。