Although igor ivanovich sikorsky was not the(1) of the helicopter. invent the ( his contribution to its development is not in doubt. important ( thousands of years ago, the chinese played with appear ( toys could fly into the air, and even da vinci drew plans for a helicopter. wood however, at that time, it was ( to build a real one. possible century, science become ( advanced enough and sikorsky was the ( technology science who made the successful helicopter a reality. as a child, sikorsky had been encouraged by his mother, a doctor, and his father, a ( to view science as a series of connected ( psychology discover today, all modem hali copter are based on his ( designs. revolution
2 importance
3 appeared
4 wooden
5 impossible
6 technologically
7 scientist
Psychologist
9 discoveries
10 revolutional