单项选择题

处理ActionEvent事件的监听器接口是（   ）。

A．KeyListener
B．ActionListener
C．MouseListener
D．ItemListener
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不定项选择
定语从句翻译成汉语时一定放在中心词前面。
A．正确
B．错误
单项选择题
Sunlight reaches us by radiation. Radiation travels in electromagnetic waves consisting of ______, and when the energy waves reach an object, they can either pass through it, or be reflected, or be absorbed, depending on the material. PVs are made out of a semi-conducting material. When they absorb photons of sunlight, the energy of the photons dislodges electrons from their atoms. The PV’s special coating attracts free electrons to the surface, and it is this movement of electrons that produces the electrical current.
A．electrons
B．photons
C．neutrons
D．atoms
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