There is an electrical problem. A classmate just plugged the lamp plug of the disconnect switch into the power socket, and the fuse on the main road blew out immediately. If the wire

A blown fuse indicates that the circuit is overloaded. There are two cases of overload, one is that the total power of electrical appliances is too large, and the other is that the line is short-circuited.

(1) If the desk lamp switch is not closed and the fuse is blown, it means that it is not the reason for increasing the use of electrical appliances, but a short circuit. So AFG is wrong.

The plug is fused when inserted into the socket, indicating that the plug is short-circuited. So BCE is wrong.

The correct answer should be D.

(2) If the fuse is blown when the desk lamp switch is closed, it may be that the total power of the electrical appliance is too large or the line is short-circuited. But according to common sense, the power of a desk lamp is very small, so adding a desk lamp will not overload. Therefore, when the topic asks the maximum possibility of failure, the possibility of excessive total power of electrical appliances is ruled out. Still short circuit.

Short circuit after closing the switch means that it is normal before closing, so CDE is wrong.

The correct answer is B.

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