Great as Newton was, many of his ideas ____ today and are being modified by the work of scientists of our time.
C
【句意】尽管牛顿非常伟大，然而他的许多观点当前正受到怀疑，并且当今的许多科学家正在努力对这些观点进行修正。
【难点】challenge意为“挑战，怀疑”，常用作及物动词。本句中牛顿的观点受到挑战为一个当前已经发生的事实，故采用现在完成时的被动语态。
ProjectHopeisanorganization_____raisesmoneytobuildschoolsandbuybooksforpoorchildren.
Everymeans____triedoutbutneverwithsuccess,asfarasmyknowledgegoes.