The word "precursor" means "preceding requirement". This means that before a student is able to take courses in Calculus, it is required that the passed all the requirements for his Algebra. Calculus is a course which involves the study on derivatives and integrals.
If a meteor were to crash to earth it would probably stir up a lot of dust, which would block out the sun
It suggests that Americans are in danger of losing their rights.
It predicts that the enemy will try to take away free speech.
It implies that the US will lose the war if Americans do not buy war bonds.
If there’s supposed to be an attachment there isn’t, but this question out of context is quite simple.
Agreement is a mixture of both parties stating their needs and wants, and through discussion and compromise. It’s finding a common ground where both parties are happy and satisfied with the outcome.