एक अलग कंडेनसर के साथ आधुनिक, कुशल भाप इंजन (steam engine) का आविष्कार करने का श्रेय किसे दिया जाता है?

In which decade was the telephone invented by Alexander Graham Bell?

In which ancient civilization was paper invented?

Around which year was the first movable type printing system invented by Bi Sheng in China?