I can't but Jesus can

Mark 9:14-29
Jesus said "O unbelieving generation",it is mean the disciples unbelieving.
Jesus said to the boy's father, "Everything is possible for him who believes."
The boy's father exclaimed, "I do believe; help me overcome my unbelief!"
Jesus healing of a boy with an evil spirit.
This kind can come out only by pray (and fast).
The evil spirit thrown him into fire or water to kill him from the boy was childhood.
Why?
The teacher of the law and arguing with disciples. What they arguing: disciples could not drive out the spirit, but Jesus could.
I can't but Jesus can.
The symptoms described here attributed to an evil spirit by Jesus's contemporaries同時代的, sound like a case of epilepsy( which modern medicine can treat but not cure)
The disciples fail because of their lack of faith.
Yet Jesus does not turn the child away because his father's faith is limited. In line with the beliefs of the time, Jesus commands the spirit to leave the boy, and he is healed. The key to success is prayer.
How?
Jesus can do everything when we believe in Him. We can do what Jesus does with pray, sometime needs fast. I can't but Jesus can even our faith is limited.
Don't lost faith when I saw the situation of Taiwan,but look upon Jesus, my hope is in hands of the Lord.