2016年托福考试阅读专项备考巩固练习四

　　Potash (the old name for potassium carbonate) is one of the two alkalis (the other

　　being soda, sodium carbonate) that were used from remote antiquity in the making of

　　glass, and from the early Middle Ages in the making of soap: the former being the

　　Line product of heating a mixture of alkali and sand, the latter a product of alkali and

　　(5) vegetable oil. Their importance in the communities of colonial North America need

　　hardly be stressed.

　　Potash and soda are not interchangeable for all purposes, but for glass-or soap-

　　making either would do. Soda was obtained largely from the ashes of certain

　　Mediterranean sea plants, potash from those of inland vegetation. Hence potash was

　　(10) more familiar to the early European settlers of the North American continent.

　　The settlement at Jamestown in Virginia was in many ways a microcosm of the

　　economy of colonial North America, and potash was one of its first concerns. It was

　　required for the glassworks, the first factory in the British colonies, and was produced in

　　sufficient quantity to permit the inclusion of potash in the first cargo shipped out of

　　(15) Jamestown. The second ship to arrive in the settlement from England included among its

　　passengers experts in potash making.

　　The method of making potash was simple enough. Logs were piled up and burned in

　　the open, and the ashes collected. The ashes were placed in a barrel with holes in the

　　bottom, and water was poured over them. The solution draining from the barrel was

　　(20) boiled down in iron kettles. The resulting mass was further heated to fuse the mass into

　　what was called potash.

　　In North America, potash making quickly became an adjunct to the clearing of

　　land for agriculture, for it was estimated that as much as half the cost of clearing land

　　could be recovered by the sale of potash. Some potash was exported from Maine and New

　　(25) Hampshire in the seventeenth century, but the market turned out to be mainly domestic,

　　consisting mostly of shipments from the northern to the southern colonies. For despite

　　the beginning of the trade at Jamestown and such encouragements as a series of acts "to

　　encourage the making of potash," beginning in 1707 in South Carolina, the softwoods

　　in the South proved to be poor sources of the substance.

　　1. What aspect of potash does the passage mainly discuss?

　　(A) How it was made

　　(B) Its value as a product for export

　　(C) How it differs from other alkalis

　　(D) Its importance in colonial North America

　　答案：C

　　2. All of the following statements are true of both potash and soda EXPECT:

　　(A) They are alkalis.

　　(B) They are made from sea plants.

　　(C) They are used in making soap.

　　(D) They are used in making glass.

　　答案：B

　　7. According to paragraph 4, all of following were needed for making potash EXCEPT

　　(A) wood

　　(B) fire

　　(C) sand

　　(D) water

　　答案：C