Hey There!
Here is your answer:
Your answer is that a experiments should be controlled because the experiment could go out of control which could harm or hurt someone.
Also the definition of a controlled experiment is a part of the experiment that's not touched.
Ex: Water is your controlled experiment that's because our not doing anything to the water.
If you need anymore help just ask me!
Hope this helps!
A place where 2 geologic units meet is called contact .
Answer:
symbiosis.
Explanation:
The term that you are referring to is symbiosis. (a symbiotic relationship)
Symbiosis is a proximate and often long-term interaction between two or more different biological species.
There are 39 trees in the park