Problem: In chemistry, pH () (potential of hydrogen) is a numeric scale used to specify the acidity or basicity of an aqueous solution. It is approximately the negative of the base 10 logarithm of the molar concentration, measured in units of moles per liter, of hydrogen ions. More precisely it is the negative of the logarithm to base 10 of the activity of the hydrogen ion. Solutions with a pH less than 7 are acidic and solutions with a pH greater than 7 are basic. Pure water is neutral, at pH 7 (25C), being neither an acid nor a base. Contrary to popular belief, the pH value can be less than 0 or greater than 14 for very strong acids and bases respectively.

pH measurements are important in agronomy, medicine, biology, chemistry, agriculture, forestry, food science, environmental science, oceanography, civil engineering, chemical engineering, nutrition, water treatment and water purification, as well as many other applications.

The pH scale is traceable to a set of standard solutions whose pH is established by international agreement. Primary pH standard values are determined using a concentration cell with transference, by measuring the potential difference between a hydrogen electrode and a standard electrode such as the silver chloride electrode. The pH of aqueous solutions can be measured with a glass electrode and a pH meter, or an indicator.
1. what does pH mean?
2. what kind of scale?
3. what does it specify?
4. what is it the negative of?
5. measured in what?
6. what are pH less than 7?
7. and more than 7?
8. what is water?
9. what degree?
10. Is it a water or a base?
11. Can pH be less than 10?
12. less than 0?
13. greater than 14?
14. What is used to measure the pH of aqueous solutions?
15. and what else?
Answer: 1. potential of hydrogen
2. numeric
3. the acidity or basicity of an aqueous solution
4. the base 10 logarithm
5. moles per liter
6. acidic
7. basic
8. neutral, at pH 7
9. 25C
10. neither
11. Yes
12. Yes
13. Yes
14. pH meter
15. a glass electrode

Problem: Muslims believe the Quran was verbally revealed by God to Muhammad through the angel Gabriel (Jibril), gradually over a period of approximately 23 years, beginning on 22 December 609 CE, when Muhammad was 40, and concluding in 632, the year of his death. Muslims regard the Quran as the most important miracle of Muhammad, a proof of his prophethood, and the culmination of a series of divine messages that started with the messages revealed to Adam and ended with Muhammad. The word "Quran" occurs some 70 times in the text of the Quran, although different names and words are also said to be references to the Quran.

According to the traditional narrative, several companions of Muhammad served as scribes and were responsible for writing down the revelations. Shortly after Muhammad's death, the Quran was compiled by his companions who wrote down and memorized parts of it. These codices had differences that motivated the Caliph Uthman to establish a standard version now known as Uthman's codex, which is generally considered the archetype of the Quran known today. There are, however, variant readings, with mostly minor differences in meaning.
1. What is the name of the book?
2. How long did it take to complete?
3. Who transcribed it?
4. Who gave the message?
5. Who spoke to him?
6. Through whom?
7. When did Muhammad die?
8. About how old was he?
9. Who established a correct type of the book?
10. What is the book regarded as?
Answer: 1. the Quran
2. approximately 23 years
3. several companions of Muhammad
4. Muhammad
5. God
6. the angel Gabriel (Jibril)
7. 632
8. 63
9. Caliph Uthman
10. Uthman's codex

Problem: CHAPTER VIII

Kate was stirring early, but not as early as her sister, who met her on the threshold of her room. Her face was quite pale, and she held a letter in her hand. "What does this mean, Kate?"

"What is the matter?" asked Kate, her own color fading from her cheek.

"They are gone--with their horses. Left before day, and left this."

She handed Kate an open letter. The girl took it hurriedly, and read--

"When you get this we shall be no more; perhaps not even as much. Ned found the trail yesterday, and we are taking the first advantage of it before day. We dared not trust ourselves to say 'Good-by!' last evening; we were too cowardly to face you this morning; we must go as we came, without warning, but not without regret. We leave a package and a letter for your husband. It is not only our poor return for your gentleness and hospitality, but, since it was accidentally the means of giving us the pleasure of your society, we beg you to keep it in safety until his return. We kiss your mother's hands. Ned wants to say something more, but time presses, and I only allow him to send his love to Minnie, and to tell her that he is trying to find the red snow.

"GEORGE LEE."

"But he is not fit to travel," said Mrs. Hale. "And the trail--it may not be passable."

"It was passable the day before yesterday," said Kate drearily, "for I discovered it, and went as far as the buck-eyes."
1. who was stirring?
2. when?
3. who got up first?
4. was she flush?
5. where did they meet?
6. who was gone?
7. what was given to kate?
8. by who
9. who left the letter
10. what was found?
11. by who?
12. when?
13. did he trust himself to say good bye?
14. was he brave?
15. what was left
16. who was the letter too?
17. who had more to say??
18. whose hand was kissed
19. who is not fit?
20. is the trail passable?
Answer: 1. Kate
2. early
3. her sister
4. no
5. threshold of her room
6. the men and their horses
7. a letter
8. "GEORGE LEE."
9. "GEORGE LEE."
10. the trail
11. Ned
12. yesterday
13. no
14. no
15. a package and a letter
16. her husband
17. Ned
18. their mothers'
19. Ned
20. It was passable the day before yesterday

Problem: One day an American called Simon went to London to visit his friend, Rick. Rick told him that his flat was on the first floor. When he arrived, Simon went straight to the first floor of the building. But he was told that there was no Rick on that floor. Do you know why? In fact, the British call the first floor of a building the ground floor. The floor above the ground floor is the first floor, while Americans would call it the second floor. The story shows that there are a few culture differences between Britain and America, though the British and Americans both speak English. The British usually hide their feelings. They seldom start a conversation with strangers. For example, on the train the British often spend their time reading newspapers or books. But Americans are quite different. They're more active and easier to talk with. The British and Americans may use different _ for many things. The British usually use "football", "eraser" and "mail" while Americans prefer to use "soccer", "rubber" and "post".
1. Who went to London?
2. Why?
3. What is the first floor called in London?
4. What type of differences are there between the UK and the USA?
5. Do the Brits express emotions freely?
6. Do they speak to people they don't know?
7. What do Brits do on their commutes?
8. what do they read?
9. What is football called in the UK?
10. What is an eraser called in the US?
11. What is an eraser called in the UK?
12. What is Simon's friend's name?
Answer:
1. Simon
2. to visit his friend
3. the ground floor
4. culture
5. no
6. seldom
7. reading
8. newspapers or books
9. football
10. rubber
11. eraser
12. Rick