The word they in paragraph 4 refers to .

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions from 44 to 50.

Some people look at an equation and see bunch of complicated numbers and symbol while others see beauty. Now, thanks to a new tool created at Carnegie Mellon University, anyone can now translate the abstractions of mathematics into beautiful and instructive illustrations.

This exciting new tool is named it Penrose after the noted mathematician and physicist Roger Penrose, who is famous for using diagrams and other drawings to communicate complicated mathematical and scientific ideas. Penrose enables users to create diagrams simply by typing mathematical expressions and letting the software do the drawing. Unlike a graphing calculator, these aren’t restricted to basic functions, but can be complex relationships from any area of mathematics. "Some mathematicians have a talent for drawing beautiful diagrams by hand, but they vanish as soon as the chalkboard is erased," said Keenan Crane, an assistant professor of computer science and robotics. "We want to make this expressive power available to anyone."

Diagrams are often underused in mathematical communication, since producing high-quality, digital illustrations is beyond the skill of many researchers and requires a great deal of time and effort. Penrose addresses these challenges by letting diagram-drawing experts turn their knowledge about creating diagrams into computer codes so that other users can access this capability using familiar mathematical language and a computer. "We started off by asking: 'How do people translate mathematical ideas into pictures in their head?'" said Katherine Ye, a Ph.D. student in the Computer Science Department who is involved in the development of Penrose. "The secret sauce of our system is to empower people to easily 'explain' this translation process to the computer, so the computer can do all the hard work of actually making the picture."

Once the computer learns how the user wants to see mathematical objects visualized — a vector represented by a little arrow, for instance, or a point represented as a dot — it uses these rules to draw several candidate diagrams. Users can then select and edit the diagrams they want from a gallery of possibilities. A special, simple – to – learn programming language was also developed so that they can easily convey the ideas in their minds to the Penrose system, Crane said. "Mathematicians can get very picky about notation," he explained. "We let them define whatever notation they want, so they can express themselves naturally."