There have been many interesting transport 32 ________. Some become popular, but others flop! The monowheel is a single-wheel bike. The driver sits inside the wheel and pedals to go forward. It has one major problem - it can 33________over very easily. I think it looks rather 34________. The Segway is a success. It's a two-wheeled vehicle. The driver pulls the handle 35________back or pushes it to go forward. It's not as popular 36________the inventors hoped, but you might see one in an airport, or park. I guess it is a convenient, green way to travel. Which new inventions will we use in the future? Which ones won't we use? It's hard to know!

32. A. invent B. inventing C. invention D. inventable
33. A. fall B. falls C. fell D. falling
34. A. simple B. weird C. friendly D. normal
35. A. go B. going C. to go D. goes
36. A.in B. from C. as D. so