Theories for why we yawn date back more than 2,000 years to the time of Hippocrates. who considered yawning to be the respiratory system's way of removing bad air' from the lungs. Centuries later, scientists claimed that yawning indicated a lack of oxygen to the brain. Today, we know that neither of these theories has strong scientific merit, prompting contemporary researchers to carry on trying to unravel the mystery of one of our most com m on biological reflexes. 

Robert Provine, a neuroscientist at the University of Maryland, points to the obvious, noting that people tend to yawn most when they are bored, hungry, and fatigued. Because all of these states can easily lead to the inability to focus on whatever task is at hand, he believes that yawning is our bodies' way of alerting us that we need to perk up. When this theory was tested, it was found that subjects did in fact tend to engage in some sort of physical activity directly after yawning, suggesting that the subjects' yawns led to their getting up and seeking out stimulation. Essentially, Provine contends that yawning occurs due to an absence of stimuli and is simply how our bodies try to regain focus. 

Then again, so many things seem to cause people to yawn that it is hardly satisfying to simply blame a lack of stimulation. One situation many of us are probably familiar with is being unable to control ourselves from yawning after seeing someone else yawn. A team of researchers from the University of Leeds headed by Catriona Morrison believe that this has to do with our inclination to show empathy for other people. In other words, if someone yawns in exhaustion, and others in the room follow suit, it is likely because they identify with and feel sympathy for the original yawner. This claim is substantiated 

by studies demonstrating that yawning is most contagious among members of the same family or social group and lowest among those with autism and psychopathy, conditions associated with the inability to empathise. 

Meanwhile, evolutionary psychologist Gordon Gallup of the University of Albany builds on both Provine's and Morrison's theories with his hypothesis that yawning developed as a way to alert group members to potential threats. Agreeing that yawning is followed by a feeling of improved attentiveness and that it is contagious, he believes that early 

humans capitalized on these effects to quickly convey the message to others that it was 

necessary to be on guard against attacks. Essentially, if everyone was yawning and feeling more alert because of it, the likelihood of falling prey to a predator was far lower. 

19. The contagiousness of yawning helped to promote alertness among members of a group. 

20. Yawning results from lack of stimuli and is a n attempt by  our bodies to refocus. 

17. The Bible's account of the origin of language is accurate.

 

18. Cultures with alphabets were no more advanced than others.

 

19. Asian writing systems were less technical than Middle Eastern ones.

 

20. In Sumer, mathematics developed separately from writing.

 ===
Để hiểu được nguồn gốc của chữ viết, cần phải lật lại một vài câu văn nổi tiếng một thời lý thuyết về ngôn ngữ và văn hóa. Thứ nhất, các ngôn ngữ không có nguồn gốc từ một
nguyên mẫu, như nhiều học giả đã đề xuất. Quan điểm đó phần lớn bắt nguồn từ Kinh thánh giải thích về nguồn gốc của ngôn ngữ và cho rằng các hệ thống chữ viết đã xuất hiện từ thời cổ đạiMesopotamia, và sau đó lan rộng và phát triển khắp phần còn lại của thế giới. Hơn nữa, các nhà xã hội học thế kỷ 19 áp dụng thuyết tiến hóa sinh học vào ngôn ngữ
sự phát triển coi chữ viết không chỉ có một tổ tiên chung mà còn thể hiện một hệ thống phân cấp tiến hóa, đặt các chữ viết theo thứ tự bảng chữ cái phía trên các biểu tượng hoặc
hệ thống viết âm tiết. Trong bối cảnh lịch sử ngôn ngữ của thế giới cổ đại, quan điểm trình bày các nền văn hóa Châu Âu và Cận Đông tiến hóa cao hơn của Châu Á, Châu Phi và Mesoamerica. Không có gì có thể được thêm từ sự thật được đưa ra đế chế giàu có về văn hóa huy hoàng, hoàn chỉnh với kiến ​​trúc tráng lệ, nghệ thuật, luật pháp, và cơ sở hạ tầng, được xây dựng bởi các nền văn minh với các chữ viết không phải chữ cái

The reason why grapefruit tastes bitter is because a substance called 9. _______contained in it. However, bitterness plays a significant role for plants. It gives a signal that a certain plant is 10. ___________. For human beings, a different person carries various genetic abilities to taste bitterness. According to a scientist at the University of Utah, 11. _______ have exceptionally plenty of 12.__________, which allows them to perceive bitter compounds. 

= =====
Grapefruit: bưởi đắng # pomelo
bitter (a): đắng
=> bitterness

substance = compound: chất
cleanse: tẩy sạch
palates: khẩu vị, vị giác
soda cracker: bánh quy mặt/ nhạt

block (v): ngăn chặn
genetic abilities : khả năng di truyền
unamy: vị bột ngọt/ mì chín => MSG: bột ngọt
savory: có hương vị ngon miệng, có hương vị mặn, có hương vị gắt, không dịu ngọt (về thức ăn)

tastebuds: nụ vị giác

Katherine 

Theories for why we yawn date back more than 2,000 years to the time of Hippocrates. who considered yawning to be the respiratory system's way of removing bad air' from the lungs. Centuries later, scientists claimed that yawning indicated a lack of oxygen to the brain. Today, we know that neither of these theories has strong scientific merit, prompting contemporary researchers to carry on trying to unravel the mystery of one of our most com m on biological reflexes. 

Robert Provine, a neuroscientist at the University of Maryland, points to the obvious, noting that people tend to yawn most when they are bored, hungry, and fatigued. Because all of these states can easily lead to the inability to focus on whatever task is at hand, he believes that yawning is our bodies' way of alerting us that we need to perk up. When this theory was tested, it was found that subjects did in fact tend to engage in some sort of physical activity directly after yawning, suggesting that the subjects' yawns led to their getting up and seeking out stimulation. Essentially, Provine contends that yawning occurs due to an absence of stimuli and is simply how our bodies try to regain focus. 

Then again, so many things seem to cause people to yawn that it is hardly satisfying to simply blame a lack of stimulation. One situation many of us are probably familiar with is being unable to control ourselves from yawning after seeing someone else yawn. A team of researchers from the University of Leeds headed by Catriona Morrison believe that this has to do with our inclination to show empathy for other people. In other words, if someone yawns in exhaustion, and others in the room follow suit, it is likely because they identify with and feel sympathy for the original yawner. This claim is substantiated 

by studies demonstrating that yawning is most contagious among members of the same family or social group and lowest among those with autism and psychopathy, conditions associated with the inability to empathise. 

Meanwhile, evolutionary psychologist Gordon Gallup of the University of Albany builds on both Provine's and Morrison's theories with his hypothesis that yawning developed as a way to alert group members to potential threats. Agreeing that yawning is followed by a feeling of improved attentiveness and that it is contagious, he believes that early 

humans capitalized on these effects to quickly convey the message to others that it was 

necessary to be on guard against attacks. Essentially, if everyone was yawning and feeling more alert because of it, the likelihood of falling prey to a predator was far lower. 

ban: cấm
anecdotal evidence: chứng cứ giai thoại
justification: bào chữa/ biện minh
forbid: cấm
playground: sân chơi

opponent: đối thủ
nut allergies: dị ứng hạt
====
remote areas: vùng xa xôi
participants: ng tham gia
invigorated and refreshed: tỉnh táo
focal point: tiêu điểm
gauge the quality: đo lường chất lượng

======
discipline: kỉ luật
rational: dựa trên lý trí
deliberative: có chủ đích

Intuitive decisions: quyết định theo bản năng
 in an instant: ngay tức thì
=====
https://study4.online/tests/18/cam-ielts-13-reading-test-1/start/

reactant: chất phản ứng

stimulation: sự kích thích.
exhaustion: kiệt sức
sympathy /ˈsɪmpəθi/: cảm thông
contagious among (sb): lây giữa/ lan truyền giữa
autism and psychopathy: bệnh tự kỷ và chứng thái nhân cách
inability to empathise. không có khả năng đồng cảm.
4. 
mines: mỏ

landfill: bãi rác

authorities = government 

comply: tuân theo

target: mục tiêu

waste levels: mức độ rác thải

incinerator: lò hỏa táng

municipal waste: rác thành phố 

burial: sự chôn

toxic waste: chất độc

impose: áp lê
n
anxious: lo lắng