Great as Charles Darwin was, his theory of evolution ______ and is being modified by the work of scientists of our time.
A.may be challenged B.is to challenge C.has been challenged D.is challenging正确答案C
Great as Charles Darwin was, his theory of evolution ______ and is being modified by the work of scientists of our time.
A.may be challenged B.is to challenge C.has been challenged D.is challenging正确答案C