$7.$ Spot welding is a technique where $\_$ is applied through electrodes to specific points, making it ideal for welding $\_$ metal sheets found in $\_\_\_$ assembly. $($Options: electrical current, pressure, heat, thin, thick, automotive$)$

$8.$ Projection welding is similar to spot welding but uses $\_$ on one of the workpieces to concentrate the welding $\_$ at predetermined points, effectively joining $\_\_\_$ layers of metal. $($Options: projections, bumps, heat, current, multiple, single$)$