78. A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by excess . (A)current (B)voltage (C)heat (D)force

59. Which of the following statements about the structure is incorrect？ (A)The arch structure is well stressed, the disadvantage is that it takes up space. (B)The truss structure uses simple materials to withstand weight, and is often used to build bridges. (C)The cable structure is cheap and beautiful, and it is often used as the main structure of the building. (D)The beam-column structure is very stable for building houses, but it takes up space and consumes materials.

78. A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by excess .
(A)current
(B)voltage
(C)heat
(D)force

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