Problem: A degree (in full, a degree of arc, arc degree, or arcdegree), usually denoted by (the degree symbol), is a measurement of a plane angle, defined so that a full rotation is 360 degrees.

It is not an SI unit, as the SI unit of angular measure is the radian, but it is mentioned in the SI brochure as an accepted unit. Because a full rotation equals 2 radians, one degree is equivalent to radians.

The original motivation for choosing the degree as a unit of rotations and angles is unknown. One theory states that it is related to the fact that 360 is approximately the number of days in a year. Ancient astronomers noticed that the sun, which follows through the ecliptic path over the course of the year, seems to advance in its path by approximately one degree each day. Some ancient calendars, such as the Persian calendar, used 360 days for a year. The use of a calendar with 360 days may be related to the use of sexagesimal numbers.

Another theory is that the Babylonians subdivided the circle using the angle of an equilateral triangle as the basic unit and further subdivided the latter into 60 parts following their sexagesimal numeric system. The earliest trigonometry, used by the Babylonian astronomers and their Greek successors, was based on chords of a circle. A chord of length equal to the radius made a natural base quantity. One sixtieth of this, using their standard sexagesimal divisions, was a degree.
1. How many degrees are in a full circle?
2. Is it an SI unit?
Answer: 1. 360 degrees
2. no

Problem: CHAPTER XLVII. DEBATING.

In the meanwhile Emily had been true to her promise to relieve Mirabel's anxieties, on the subject of Miss Jethro. Entering the drawing-room in search of Alban, she found him talking with Cecilia, and heard her own name mentioned as she opened the door.

"Here she is at last!" Cecilia exclaimed. "What in the world has kept you all this time in the rose garden?"

"Has Mr. Mirabel been more interesting than usual?" Alban asked gayly. Whatever sense of annoyance he might have felt in Emily's absence, was forgotten the moment she appeared; all traces of trouble in his face vanished when they looked at each other.

"You shall judge for yourself," Emily replied with a smile. "Mr. Mirabel has been speaking to me of a relative who is very dear to him--his sister."

Cecilia was surprised. "Why has he never spoken to _us_ of his sister?" she asked.

"It's a sad subject to speak of, my dear. His sister lives a life of suffering--she has been for years a prisoner in her room. He writes to her constantly. His letters from Monksmoor have interested her, poor soul. It seems he said something about me--and she has sent a kind message, inviting me to visit her one of these days. Do you understand it now, Cecilia?"

"Of course I do! Tell me--is Mr. Mirabel's sister older or younger than he is?"

"Older."

"Is she married?"

"She is a widow."

"Does she live with her brother?" Alban asked.

"Oh, no! She has her own house--far away in Northumberland."
1. What was wrong with Mirabel?
2. about what?
3. Was anyone going to help?
4. Who did she se in the drawing room?
5. Where was Emily before the drawing room?
6. Was she speaking to Mr. Mirabel?
7. about what?
8. Did they know her?
9. Does she live with him?
10. Where does she live?
11. Is she happy?
12. why not?
13. why?
14. Does Mr. Miraell talk to her?
15. Does he visit her home?
16. How do they communicate?
17. Who was invited to visit her?
18. Does his sister have a husband?
19. wife?
20. Does she live in an apartment?
21. Is she older?
Answer: 1. Anxious
2. Miss Jethro
3. Emily
4. Alban and Cecilia
5. rose garden
6. Yes
7. his sister
8. No
9. No
10. Northumberland
11. No
12. sister lives a life of suffering
13. she has been for years a prisoner in her room
14. Yes
15. unknown
16. By letter
17. Emily
18. No
19. No
20. No
21. Yes

Problem: The mystery stories of Sir Arthur Conan Doyle are famous all over the world. The detective in his stories is called Sherlock Holmes. He solves mysteries in a most surprising way. His assistant, Dr Watson, watches with admiration and then writes up the story of the mystery afterwards. This is a useful story writing skill. Because Watson is not very clever, the story remains a mystery until the end. The readers can sometimes pick up some clues before he does! Then, to make Watson understand the mystery, Holmes has to explain it all, step by step. So we, the readers, get to see it step by step too. Watson is almost as good a character in the story as Sherlock Holmes! The very first time they meet, Holmes greatly surprises Watson. When they are first introduced, Holmes says to Watson, 'How do you do? I see you have been to Afghanistan .' Watson is too amazed by this to ask Holmes how he knows this. Watson has, indeed, been to Afghanistan. Later, he asks Holmes about it. Holmes explains that there is nothing magical about what he does. He gets to know it all by very, very careful observation . Observation One Watson was introduced to Holmes as a doctor. Yet Holmes thought that the way he stood and walked made him seem like a soldier. So, this meant he was probably an army doctor. Observation Two Watson's face was quite dark skinned. But his wrists were pale. So his dark face was probably sun burnt. This meant that he had been to a hot, sunny country. Observation Three At the time, the British army had soldiers at bases in many parts of the world. So there were still a lot of places to choose from. However, Holmes saw that Watson looked very tired and he was always holding his left arm, as if it was painful. So, he had probably been with the army to a place where they were fighting. There was only one place where the British army was fighting at that time: Afghanistan.
1. who is the writer?
2. is he well known?
3. who is the main player in his books?
4. does someone help him?
5. who?
6. does the main character have a job?
7. what?
8. how did he surprise his helper when they first met?
9. was his helpers skin milky and white?
Answer:
1. Sir Arthur Conan Doyle
2. Yes
3. Sherlock Holmes
4. Yes
5. Dr Watson
6. Yes
7. detective
8. Knowing he went to Afghanistan
9. No