Salt
Salt is a remarkable (remark) thing. It is a basic element in the diet of humans. It is also necessary for_____（41）(animal) and plants. It is one of the most_____（42）(effect) and most widely used of all food preservatives（防腐剂）. Its industrial, _____（43）(medicine) and other uses are almost countless. In fact, salt has been a(n)_____（44）(importance) element of life. It also has been the subject of many stories. It is_____（45）(frequent) mentioned in fairy tales. Some cultures give magical power to salt. In the past, salt_____（46）(serve) as money at various times and_____（47）(place). Salt has been the cause of bitter wars. In many cultures, _____（48）(offer) bread and salt to Visitors is a_____（49）(tradition) sign of welcome. Salt-making_____（50）(cover) much of the history of Europe since Roman times.
44._____