弦: bow string, string of musical instrument, watchspring, chord (segment of curve), hypotenuse...
双向: bidirectional, two-way, interactive...
伟大: huge, great, grand, worthy of the greatest admiration, important (contribution etc)...
外国: foreign (country)...
珍藏: collection, to collect (valuables)...
城镇: town, cities and towns...
