50. Which of the following terms is defined in the passage?
(A) fossil record (line 3)
(B) laminae (line 13)
(C) varves (line14)
(D) glacial episodes (line 29)

46. According to the passage, the layers in varves are primarily formed by (A) fossilized bacteria (B) pieces of ancient dropstones (C) a combination of ancient and recent sediments (D) annual cycles of sediment transport and deposition

47. The phrase “the other” in line 17 refers to another (A) annual cycle (B) glacial lake (C) layer of sediment (D) season

48. According to the passage, the presence of dropstones indicates that (A) the glacial environment has been unusually server (B) the fine-grained sediment has built up very slowly (C) there has been a global ice age (D) coarse rock material has been carried great distances

49. Why does the author mention Canada, North America, Africa, India, and Europe in lines 23-24? (A) To demonstrate the global spread of dropstones (B) To explain the principles of varve formation (C) To provide evidence for the theory that there was a global ice age in the early Proterozoic eon (D) To illustrate the varied climatic changes of the Proterozoic con in different parts of the globe

1. Which of the following aspects of glass fiber does the passage mainly discuss? (A) The major developments in its production (B) Its relationship with pottery making (C) Important inventors in its long history (D) The variety of its uses in modern industry

2. The word "coarse" in line 1 is closest in meaning to (A) decorative (B) natural (C) crude (D) weak

3. Why was there nothing written about the making of Renaissance glass fibers until the seventeenth century? (A) Glassmakers were unhappy with the quality of the fibers they could make. (B) Glassmakers did not want to reveal the methods they used. (C) Few people were interested in the Renaissance style of glass fibers. (D) Production methods had been well known for a long time.

4. According to the passage, using a hot glass tube rather than a wheel to pull fibers from molten glass made the fibers (A) quicker to cool (B) harder to bend (C) shorter and more easily broken (D) longer and more durable

5. The phrase "this material" in line 16 refers to (A) glass fibers (B) decorations (C) ornaments (D) novelties for collectors

6. The word "brittle" in line 17 is closest in meaning to (A) easily broken (B) roughly made (C) hairy (D) shiny