<span> The main source of energy for humans is the food we eat.</span>
Explanation:
leave is the base of the verb to leave left is the past simple and the past participle form of the verb it used in the pasta simple verb tense and the present perfect verb tense you learn how to use this structures in the lesson
Answer and Explanation:
Darwin observed that members of a species in a population especially those that reproduce sexually show certain variations. Some of these variations are caused by genes hence can be inherited. Some of the inherited characteristics make the individuals possessing them better suited to the prevailing environmental conditions. This enables such individuals to stand a better chance to survive in the struggle for existence. Accumulation of this gradual changes in a populations due to natural selection leads to formation of new species that are better suited to the environment.
After wind erosion, the igneous rock turns to sediment. It may be dropped into a river where the sediments go through cementation and compaction. Then it become a sedimentary rock. This cycle goes on forever. It is called the rock cycle.