The quote states that we should be using solar energy before our limited amount of naturally occurring oil and coal runs out. Meaning; we should be proactively working towards solar power rather than to wait for our resource to run out to start.
The effects of acid rain are most clearly seen in the aquatic, or water, environments. For an example, streams, lakes, and marshes.Acid rain flows to streams, lakes, and marshes after falling on fields, forest, roads, and buildings. Acid rain also directly falls on aquatic habits.
Answer:
immigration help to a country to grow their labor or taxes
Explanation:
Immigrants also make an important contribution to the U.S. economy. Most directly, immigration increases potential economic output by increasing the size of the labor force. Immigrants also contribute to increasing productivity.
Answer:
b. flat rotation curves in spiral galaxies
Explanation:
Dark matter accounts for majority of the matter in the universe (about 85%). It is considered to be composed of subatomic particles which are yet to be discovered. Dark matter cannot be observed because it does not emit light that can be detected. Only its gravitational effect is visible.
Astronomers when calculated the mass of the visible matter and tried to account for the observed speed of stars in the galaxy, there was a mismatch. To understand what caused this mismatch, astronomers gave name to the invisible matter as the Dark Matter.
The expected velocity of stars should decrease away from the near the center of the galaxy but a constant velocity of stars was observed that is a relatively flat rotation curve was obtained.
Thus, flat rotation curves in spiral galaxies in an evidence of Dark Matter.
Channel Tunnel, CN Tower, Empire State Building, Golden Gate Bridge, Itaipu Dam, North Sea Protection Works (Netherlands), Panama Canal. Hope this helps!
