A-A+
The passage implies that________.A．LED bulbs a
问题详情
The passage implies that________.
A．LED bulbs are still expensive at present
B．the task of making LED the main source of artificial light is too difficult
C．LED traffic lights are used everywhere in the world
D．in order to fulfill the task of making LED the main light source, lightbulb makers have to work together with semiconductor manufacturers请帮忙给出正确答案和分析，谢谢！
参考答案
正确答案：A
解析：这道题需要分析判断。最后一段说，研制出节能，廉价，美观的白色发光二极管是一个艰巨的挑战。再联想到文章前面提到，美国的交通指示灯换上了节能耐用的二极管，而发展中国家还都用白炽灯。那么新能源的症结就是不廉价, 这一判断与选项A相符。
