How to use "examination" in a sentence

His time was enormously valuable to the country; his work was sensitive and often-required urgent decisions based upon first-hand examination of information to be found only in distant places

He was a medical student, working for an examination, and he heard nothing of the arrival until Saturday morning

He returned and tried to concentrate on his examination notes, but without success

I learned nothing new except that already in one week the examination of the Martians' machines had produced amazing results