'hard to do' or 'hardly to be done'

If I want to say something is hard to achieve, which one is right?
(1) 'Control of steering wheel is important for driving. It is hard to achieve by children'
(2) 'Control of steering wheel is important for driving. It is hard to be achieved by children'
(3) 'Control of steering wheel is hard to achieve by children'
(4) 'Control of steering wheel is hard to be achieved by children'
(5) 'It is hard to control steering wheel by children'
(6)  'Steering wheel is hard to be controlled by children'
(7) 'Steering wheel is hardly controlled by children'
(8) 'Steering wheel is hard to control by children'
(9) 'Steering wheel is hardly to be controlled by children'

Which sentences are wrong? Why? It is hard for me to distinguish these sentences. Thanks a lot.