tailieunhanh - Toefl preparation for the computer and paper test part 66

Tham khảo tài liệu 'toefl preparation for the computer and paper test part 66', ngoại ngữ, toefl - ielts - toeic phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | RECORDING SCRIPT 639 you can see in the diagram the crust is quite thin. The crust is about 20 miles thick under land masses. Under the oceans the crust is even thinner. The crust is only about 4 miles thick under the oceans. Now let s talk about the mantle. The mantle makes up the greatest part of the earth. The mantle is about 1 800 miles deep. It s made of stony materials that were created from silicate minerals. The mande is a huge mass of stony material. Now we ll look at the core which actually has two distinct parts the outer core and the inner core. Neither the outer core nor the inner core is as wide as the mantle the outer core is less than 1 400 miles wide and the inner core has a radius of 800 miles. The outer core is a layer of liquid metal it definitely has liquid nickel and iron and it may have other substances. The outer core is the only liquid layer. The inner core is composed of nickel and iron as the outer core is but the inner core is not a liquid layer like the outer core. It is extremely hot at the inner core but there s also an extreme amount of pressure on the minerals in the inner core that keeps them firm rather than liquid. That is all for our overview of the various layers that make up the earth. We ll be having a quiz on the material next class so be prepared. 6. HOW THICK IS THE CRUST 7. WHAT ARE EACH OF THE LAYERS COMPOSED OF 8. WHICH LAYER IS 1 800 MILES WIDE 9. WHAT MINERALS ARE IN THE CORE 10. APPROXIMATELY HOW FAR IS IT FROM THE SURFACE OF THE EARTH TO ITS CENTER Question 11-16 narrator Listen to a lecture in a linguistics class. The professor is talking about the history of the letter c. professor The letter c in today s English has two very different pronunciations. It can be pronounced like a k as in the words car can or coal. It can also be pronounced like an s as in the words cent circle or cease. Let s look at the history and development of the letter c to understand how these two very different pronunciations for one letter