皮皮学，免费搜题
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搜题
【单选题】
The exercise is not difficult but just needs care and patience.A.
by itself
B.
of itself
C.
in itself
D.
for itself
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参考解析：
知识点：
皮皮学刷刷变学霸
举一反三
【多选题】What are the main principles on which the US government system is established?
A.
federalism
B.
seperation of powers
C.
constitutional monarchy
D.
respect for the Constitution and the rule of law