We have 20 different amino acids in our bodies.
Answer:
The climate of Antarctica was probably much warmer in the past than it is today.
Explanation:
There are little things living there now. Coal takes millions of years to form. There must have been much more living things there in the past (when it was warmer) to make coal.
Answer: the Earth's spheres interact with other planets in the universe
Explanation: the Earth has different layers and its atmosphere and then when it is in contact with the outer space it can rotate around other planets
Answer: Interventional Study
Explanation: When a treatment group is compared to standard (control) group it is called Interventional Study
