밑줄 친 부분에 들어갈 말로 가장 적절한 것은? The first commercially successful steam engine was built in England in 1712, but it was very slow. Then an inventor named James Watt came up with crucial innovations. His engine was faster and more efficient at driving machinery. By 1800 about 500 of Watt's steam engines were chugging and hissing in mines and factories throughout Britain. The widespread use of steam engines began when inventors put them to use in the textile mills. Using steam power instead of water power meant that factories no longer had to be built near ready supplies of water. ____________, they could be located where fuel was readily available and where workers already lived. Also, factories could be built closer to roads and ports from which raw materials and finished products could be shipped.