Who a theory about black holes?A. put forwardB. put downC. put awayD. put off

网友回答

(答案→)A. put forward
B. put down
C. put away
D. put off
解析：考查词组辨析：A．put forward提出，B．put down放下，记下，C．put away收好，D．put off推迟，句意是：谁提出了黑洞的理论？选A。