instruction:
In this task, you are given a question and an answer, you would be asked to create the sentence based on the Question-Answer provided. It should be contained within the Question-Answer provided.
question:
Question: What is the predicted year that as many as half of all remaining species could go extinct? Answer: 2050
answer:
2050 is the predicted year that as many as half of all remaining species could go extinct.


question:
Question: Why do birds need a light-weight body? Answer: to stay aloft
answer:
Birds need a light-weight body for to stay aloft.


question:
Question: Expansion of a gas into a vacuum is irreversible because the external pressure is measurably less than the internal pressure of the gas, and no states of what exist? Answer: equilibrium
answer:

Expansion of a gas into a vacuum is irreversible because the external pressure is measurably less than the internal pressure of the gas, and no states of equilibrium exist.