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【单选题】
化简cos ( 6k+1 3 π+2x) +cos ( 6k-1 3 π-2x) +2 3 sin ( π 3 +2x) （k∈Z）的结果为（ ）A.
2sin2x
B.
2cos2x
C.
4sin2x
D.
4cos2x
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知识点：
皮皮学刷刷变学霸
举一反三
【单选题】---John, how does your father usually go to work ? ---_____________.
A.
He usually goes to work by underground.
B.
He usually goes to work from Mondays to Fridays.
C.
He usually goes to work with my mother.
【单选题】my father is usually _____ home _____ Sundays. [ ]
A.
in, in
B.
at, at
C.
/ , in
D.
at, on
【单选题】On ,I usually buy presents for my father.
A.
Fathers' Day
B.
the Fathers' Day
C.
Father's Day
D.
the Father's Day
【简答题】中国第一条办理营业的铁路是____
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