السؤال 849

The signal of a general alarm at a railway crossing is a series of:

Two long and two short signals.
One long and three short signals.الإجابة الصحيحة
Three long and three short signals.
Three long and one short signal.

الشرح

The railway-crossing general alarm uses one sustained sound followed in sequence by a group of three short sounds. Patterns with equal groups, or with the long sound placed after several short ones, do not match the standardized warning that others are expected to recognize.

الشرح

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