What two key factors that cause labor productivity to increase over time?

One pretty straightforward answer could be investment to physical and human capital. But if you are if you are working with a mathematical model the answer to your question depends on the specific model. For example, in an equilibrium model from economic theory, you could find the determinants of labour productivity by taking the partial derivative of the production function with respect to the amount og labour.

Not true it depends on the person

In financial aspects, a depression is a sustained, long haul downturn in monetary movement in one or more economies. it is a more extreme monetary downturn than a recession, which is a slowdown in financial action through the span of a typical business cycle. a depression is an irregular and extreme type of recession. so depression is always followed by recession but it is not correct to state that a depression always follow a recession.