Do you know who invented light bulb?bulb要不要用复数?还有This chair is made of metal and wood.metal要不要用复数？

Do you know who invented light bulb?bulb要不要用复数?
还有This chair is made of metal and wood.metal要不要用复数？

bulb不需要用复数.只是表示灯泡这种物体.例如：Edison invented the light bulb.
爱迪生发明了电灯泡.（金山词霸）
metal也不用,在这里只是表示某种材料.

不用