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多选题
Given two collection objects referenced by col1 and col2,which of these statements are true?()
A

The operation col1.retainAll(col2) will not modify the col1 object.

B

The operation col1.removeAll(col2) will not modify the col2 object.

C

The operation col1.addAll(col2) will return a new collection object, containing elements from both col1      and col2.

D

The operation col1.containsAll(Col2) will not modify the col1 object.


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