无人机最激动人心的应用还没有被发明出来。
The most exciting applications of drones haven't even been invented yet.
The process of grouping, of organization, is not arbitrary but follows definite laws.
The only true wisdom is in knowing you know nothing.
The real moral test of a society is how it treats those who are at the dawn of life, the children; those who are in the twilight of life, the aged; and those who are in the shadow of life, the sick, the needy and the handicapped.