The human is unaware of how weak he is until he is sick

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" الإنسان " the human ( al ensan )
" لا " no ( la )
"يعلم " know (ya'lam )
" كم " to what extent (kam )
" هو " he (howa )
" ضعيف " weak (da'ef )
" إلا " but (ela )
"عندما " at the time when ('endama )
" يمرض " is infected by an illness (its present verb ) (yamrad )