What is an expense that changes month to month

Me i really need which of these was an accomplishment of the han dynasty? the invention of the seismograph finding a water passage to europe the invention of the ballpoint pen the invention of the abacus

In the space provided, analyze the pros and cons of establishing smaller ethnic communities within larger communities like chinatown and little italy. use evidence to support your reasoning.

One drawback of voluntary trade is that it a.requires two groups to use a common language b.can make one group dependent upon another for necessary goods c.doesn't occur unless there is a shortage of goods for at least one group d.forces groups to rely on themselves to produce all the goods they need