激光焊接时，由于热源是一束光，焊接时不需与焊件做电接触。
参考答案：对
The general benefit of the GMDSS is to（）.
A.enable SAR operations to start with minimum delay
B.give facilities to marine communication
C.reduce sharply the chances of ship’s sinking
D.both A and C
如何使用加压包扎止血法？
