Three objects are brought close to one another, two at a time. When objects A and B are brought together, they attract. When objects B and C are brought together, they repel. Which of the following are necessarily true?
A: Objects A and C possess charges of the same sign.
B: Objects A and C possess charges of opposite sign.
C: All three objects possess charges of the same sign.
D: One object is neutral.
E: Additional experiments must be performed to determine information about the charges on the objects.
A: Objects A and C possess charges of the same sign.
B: Objects A and C possess charges of opposite sign.
C: All three objects possess charges of the same sign.
D: One object is neutral.
E: Additional experiments must be performed to determine information about the charges on the objects.
举一反三
- Which of the following statements are true？（） A: The equals（） method determines if reference values refer to the same object. B: The == operator determines if the contents and type of two separate objects match. C: The equals（） method returns true only when the contents of two objects match. D: The class File overrides equals（） to return true if the contents and type of two separate objects match.
- Which three objects can be components of a menu module?（） A: windows B: parameters C: object groups D: report objects E: visual attributes
- Aristotle thinks types differ from one another in three ways: the means, objects and _____.
- Objects have the property of ______ —although objects may know how to commu- nicate with one another across well-defined interfaces, they normally are not allowed to know how other objects are implemented.
- Which three objects can be components of a menu module?（） A: Awindows B: Bparameters C: Cobject groups D: Dreport objects E: Evisual attributes