Qin shihuangdi became the first emperor of china around the year 221 bc after he successfully united the country under a single government. previously, china was a loose collection of states constantly at war. qin shi huangdi assumed control of the individual states and replaced their leaders with his own supporters. he forced the old rulers of the states to live in the capital city where he could watch them. to further unite china, qin shi huangdi implement a standard writing system and a standard system of weights and measures. according to the excerpt, in what way did qin shihuangdi maintain power