infirmity
n[C, U]
(particular form of) weakness 体弱; 虚弱; 衰弱
Old age and infirmity had begun to catch up with him. 他开始显出年老体衰的样子了.
infirmity of purpose 意志薄弱
Deafness and failing eyesight are among the infirmities of old age. 耳聋眼花是年老体衰的现象.
One should travel out of his own country at least once.
我们至少应该离开自己的国度去旅行一次。
it requires 97 per cent less energy to travel the quarter of a million miles from the Moon to Earth-orbit than the 200 mile-journey from Earth's surface into orbit!