Final answer:
The question pertains to the correct operation of a miter gauge in an engineering or woodworking setup, and the word to complete the sentence is 'smoothly', indicating the desired movement of the gauge for precision and safety.
Step-by-step explanation:
The question relates to ensuring proper use of a measuring tool in an engineering or woodworking context. Specifically, it appears to be addressing the use of a mite gauge (more commonly referred to as a miter gauge) which is a tool used to hold workpieces at a set angle while being passed through a cutting tool such as a saw. The blank in the sentence should be filled in with an adverb describing how the mite gauge should slide down the guide slot.
A commonly required manner for such tools to move is smoothly to prevent any jarring movements that could affect the precision of the cut. Therefore, the complete sentence should read: "Be sure the mite gauge slides smoothly down the length of the guide slot before you start to cut." This ensures precision and safety when making cuts.