According to the passage, which of the following can be found in areas with quite different climatic conditions on Earth

A．the desirers are often insensitive to the operational complexities of their machines
B．the range of features provided is unlimited
C．there is no ideal way of controlling quality
D．their designers often ignore the complaints of their uses

A．he had neglected the importance of using the timer
B．the machine had far more technical features than necessary
C．he had set about using it without proper training
D．its operation was far more difficult than the designer intended it to be