What about( )a bike

What about( )a bike What about riding a bike? what'a the hardest thing about learning toride a bike? what about with your bike? what about going thereby bike?go ahead What about going bike r_ on Sunday. What is the hardest thing about learning to ride a bike What’s the hardest thing about learning to ride a bike? What's the hardest thing about learning to ride a bike? My bike is brken .What about()?a:your,b:yours,c:you,d:he. How about going for a bike His bike is quite different ( )mine.What about yours?