If a consumer wants a quick settlement of his problem, it's better to complain to （）

A．showing the faulty item to the manufacturer
B．explaining exactly what is wrong with the item
C．saying firmly that the item is of poor quality
D．asking politely to change the item

A．although robots can do much dangerous and tiring work, humans are superior
B．although humans are superior, robots can do much better in many areas of work
C．robots will replace humans in more and more fields
D．robots are superior to humans because they can do much work that humans can't do