The short answer: 20 (composite score) is the national ACT average. About half of students score above that, and half of students score below. The top 25% of ACT takers score about 24 or more, so if your score is above 24, that's excellent.
1 SavinâNorov machine gun. 2  Space Network, a NASA relay satellite system. 3  Sthene, an obsolete unit of force or thrust in the metre-tonne-second system of units. 4  Substantia nigra, a brain structure. 5  Supernova, a stellar explosion, in astronomy and cosmology.  Tin, a metallic element with chemical symbol Sn.
The Autonomic Nervous System includes the Sympathetic Nervous System (SNS) and the Parasympathetic Nervous System (PNS). The SNS is responsible for the Flight or Fight response of the body. When we get scared, the SNS increases our heart rate and provides energy to our muscles in preparation for action.