$11.$ High$-$frequency resistance welding is utilized for $\_$ speed welding operations, employing $\_$ current to heat the material, often used in the production of $\_$ and $\_.($Options: high, low, alternating, direct, pipes, tubes$)$

$12.$ In Gas Tungsten Arc Welding $($GTAW$),$ a $\_$ electrode made of $\_$ is used to weld $\_$ materials, offering high precision and quality in industries such as $\_$ and $\_\_\_.($Options: non$-$consumable, consumable, tungsten, steel, thin, thick, aerospace, automotive$)$