ABB保护闭锁可以分为（）闭锁。
A.X
B.Y
C.S
D.Z
参考答案：A, B, C, D
—Look at my new digital camera. I bought it _____ June 1, Children's Day.
—Wow, how nice![ ]
A. on
B. in
C. at
D. for
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