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.

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

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)

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

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

7. The production of glass fibers was improved in the nineteenth century by which of the following (A) Adding silver to the molten glass (B) Increasing the circumference of the glass tubes (C) Putting silk thread in the center of the fibers (D) Using yam reels

8. The word "appreciated" in line 23 is closest in meaning to (A) experienced (B) recognized (C) explored (D) increased

9. Which of the following terms is defined in the passage? (A) invention (line 7) (B) circumference (line 17) (C) manufacturing process (line 24) (D) bushing (line25)