Explain how a thumbtack is designed so that you do not have to use a lot of force to push it through paper or the surface of a bulletin board.​

there is an explationation of this on a site called crash   course world history 1

this is a pretty broad question and can be a pretty lengthy answer. since 1900, women have gained a lot more rights and have become active in the workforce. with women being in the workforce, men play a larger role in family life. many family tasks are shared between men and women, whereas, women used to be the sole family caretakers.

that should get you started at least.

answer; the intervening variable;