Lincoln accomplished all of the following except *.

Which two statements are true about a system? 1. a system is a group of objects analyzed as one unit. 2. energy that moves across system boundaries is conserved. 3. there’s only one way to define the boundaries of a system. 4. all systems are made by humans.

Remote sensing of the earth's surface and atmosphere may involve the use of what type of instruments?

The authors use the word “backbone” in lines 3 and 39 to indicate that