What are smart windows, according to Paragraph 4 ?A．Windows that are coated.B．Windows that are glazed.C．Windows the color of which can be changed.D．Windows that have many layers.
题目
What are smart windows, according to Paragraph 4 ?
A．Windows that are coated.
B．Windows that are glazed.
C．Windows the color of which can be changed.
D．Windows that have many layers.