Answer:
If their writing dissapears, then, what is known about that civilization is also likely to dissapear, unless their previous writing was preserved in some other way.
This is something that has actually happened often in history. For example, the library of Alexandria, in Egypt, was the largest library of the Ancient World, and it was burned down by Caliph Omar in 642 AD. Countless works by Ancient authors, that gave account of civilizations, cultures, philosphies, and religions, were lost, and there is no plausible way to recover such knowledge in the current era.
I am more hopeful in the future because i feel that are new president is going to turn things around and make things a lot better for everyone :)
Heat causes chemical reaction so that might be a way in which people use chemical properties to separate one substance from another substance .
The fourth alternative is correct (D).
Nations produce goods and services according to their productive capacity, their natural resources and the specialization of the workforce. In this way, some goods and services are expensive for a nation to produce, but are cheaper for other nations to produce.
Thus, if each nation specializes in the product in which it has a production advantage, nations can make tradeoffs. The country that has an advantage in the production of a good can export it to other countries and still can import the goods to which it is not specialized.