What prevented the Roman Empire from expanding farther into Europe, Britain or Asia?

Why is mary salter ainsworth a central figure in psychology?

Ineed your opinion for the question of what is your thoughts on the use of medical marijuana? (social experiment)

Which questions should robert ask himself before investing the $10,000 he inherited? check all that apply. how am i protected as an investor? are my friends investing in a similar way? what guarantees are in place so i make money? what taxes will i have to pay on this investment? how do the risks compare to the potential gains? what are the chances that the investment will fail?