题目内容：
根据以下资料，回答题。
After Man has dreamed about flying for a long time．Michael Moshier is a dreamer．He invented the Solo Trek.The Solo Trek had a 120 horsepower engine with twin fans．Only one person flies．As you fly above the roofs, you lean a little forward．You can see everything under you．You are flying like Superman.
Michael Moshier looked at the jet belt and the rocket belt that was developed 20-30 years ago Nothing ever came from them．People still can't fly.
Inventors have tried to make it easy for people to fly．Paul Moller has been working on his flying car for 30 years．He now says it is ready for tests．It would take off and land vertically, go600 miles an hour, and deliver 20 miles to the gallon．A computer would do the actual flying．He says it could be sold next year for about a million dollars.
NASA is working with Moshier to help develop his flying machine．The first users are likely to be military.
It's been 50-years since Robert Fulton invented his airphibian, a flying car．It flew, and is now in the Smithsonian Museum.
Getting dreams to fly is never easy.
The Solo Trek is able to lift off the ground by using __. A． a solar powered engine
B． engine-powered twin fans
C． large flapping wings
D． rotating blades
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