问题
选择题
As is known to all , theory is based on practice and _______ serves practice.
A．by chance
B．by turn
C．in return
D．in turn
答案
答案：D
短语辨析。by chance偶然；by turn轮流；in return作为回报；in turn轮流，依次，转而，反过来。句意：众所周知，理论以实践为基础，反过来又应用于实践。所以选D。