A student has the high-power lens in position and appears to be intently observing the specimen. The instructor, noting a working distance of about 1 cm, knows the student isn't actually seeing the specimen. How so?

Explanation:

Based on this the student is out if the focus, and just viewing on  the dust.Basically, high -power lens is a non oil immersion lens, with a short working distance  of 1cm,which  will be about  a few millimeters.Hence the student will be out of focus, just carry out a fruitless effort  focusing on the dust, missing the focus on the specimen.

stress fractures occur largely in the feet and legs and are common in sports that require repetitive impact, primarily running/jumping sports such as gymnastics or track and field.

after receiving a stimus, the sensory receptors send(s) signals to the appropriate area of the body.  

the must be sensory neurons.  

hope its .