Earth's interior is made of several different layers. Which problem does this model of Earth solve? A. Earth's interior layers formed too long ago to observe directly B. Finding out what makes up Earth's layers requires special tools. C. Earth's interior is very hot and too dangerous to study directly. D. Taking a picture of Earth's interior is impossible.

If a force of 40 newtons moves a cart a distance of 9 meters, the work done is nm. if the same force moves the same cart three times that distance, the work done is nm.

The images show two species of tree frogs in a particular region. the gray tree frogs are adapted to the trees of the woodlands, while the green tree frogs can survive in woodlands or grasslands. the gray frog was abundant in the woodlands. because of climatic changes, most of the trees in the region died, and the woodlands changed to grasslands. in such a case, the . the gray tree frog is closely related to the green tree frog genetically, but they have different mating calls. this suggests that speciation occurred because of .

Why do you suppose the structural polysaccharide cellulose does not contain branches?