在水下进行金属切割underwater cutting

• 先割后淹水，而非在水下淹割是因为水下切割操作性较差。

  Cutting is followed by flooding rather than underwater cutting because such operations are difficult.

• 直升机体型一般较小，不需要在水下切割。

  The body of a helicopter is generally small and does not require underwater cutting.