Im Applicating for a Working Holiday Visa.=I'm Applying for a Working Holiday Visa.
I had a problem.
I had tuberculosis. but now cured.=I had a tuberculosis but now it's cured.
what can i write it?=What can i write it?
I will write these sentences.
plz check sentences.=Please check my sentences.

I had tuberculosis 4years ago.=I had a tuberculosis 4 years ago.
When I took medicine for 6month.
I`m healthy now.=When I took some medicine for 6 months I became healthier.

How do I writing better?= How do I write better?

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If they ask you about your health, you can honestly say that you had a disease before but you are already cured.You folowed docto's advice, tried to improve your health and eventually recovered. Tell them, you are physically fit enough to the position that you are applying for and you can do your work effectively.