Flammability is a materials ability to burn in the presence of

one of the most common forms of pain or discomfort we feel during strenuous exercise is a burning sensation in our lungs or muscles that goes away shortly after we cease the activity. this is caused by a build-up of lactic acid.

the cladogram shown here shows similarities and differences among several classes of vertebrates. anatomically, the four have limb structure as their common ancestor. we might separate the mammals from the other three classes because they a) divergent; do not lay eggs b) identical; are warm-blooded c) varied; a four chambered heart d) homologous; have mammary glands