In some places, especially some new wells that have just been drilled,
the oil is under pressure, and it brings itself to the surface as soon as
you drill a 'pipe' for it to rise through.
In most oil wells, there's a pump bobbing up and down day and night,
pumping the oil up out of the well.
When the well is so old that even a pump isn't very effective, water is
often forced down the well under pressure, and the water forces the
oil back up through the pipe.
Answer:
The Last Universal Common Ancestor (LUCA) is the most recent common ancestor of all current life on Earth, estimated to have lived some 3.5 to 3.8 billion years ago
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Explanation:
I believe the answer is b.
As the bear enters hibernation, its metabolic processes such as body temperature, heart rate, and respiratory rate are reduced. But bears do not lower the body temperature as much as once thought. Their hibernation temperature is around 88 degrees and waking temperature is 100 degrees F. This relatively high sleeping temperature allows bears to become fully alert if aroused, perhaps to enable the bear to protect itself from predators and other dangers without unnecessarily taxing their energy reserves. Over the course of a hibernating season it is thought that bears use approximately 4 thousand calories a day, which results in a weight loss of about 20 percent of it body weight by spring.
