​​ II​​ . VOCABULARY AND DEPRESSION
Choose one word or phrase - a, b, c​​ or d -​​ that best completes​​ the​​ sentence or substitutes for the
underlined word or phrase.
11. Some whales migrate into warm waters to bear their....................​​
a. youngb. diets c. calves d. young whales​​
12. Whales feed on​​ krill.
a. tiny shellfish b. small fish c. sea plants d. small animals
13. .................... is the variety of different types of plant and animal life in a particular region.
a. Interaction b. Herbicide c. Environment ​​ d. Biodiversity
14. He is a .......... biologist. He spends all his life studying​​ sea plants and animals.
a. ocean b. marine c. botany d. sea
15. ......................is a chemical used for killing- weeds.
a. Pesticide b. Herbicide c. Fertilizer d. Antibiotic
16. We all enjoyed the waters of Timor Sea and the coral reefs that lie ...................
a. under b. behind c. beneath d. beside
17. Some tiny organisms are ................... along by the currents.
a. carried b. taken c. flowed d. moved
18. Sperm whales are ................, which means they eat meat.
a. herbivoresb. carnivores c. omnivores d. mammals​​
19. Sperm whale population are​​ at risk​​ due to hunting.
a. in extinction b. in danger c. on the decrease​​ d. in fewness
20. These birds..........................to North Africa in winter.
a. settle b. go c. relocate d. migrate

A. Choose the word that has the underlined (letters) pronounced differently from the others.

1. a. gulf ​​ b s urface c. s ubmarine d. c urrent
2. a. ocean b. unders ea c. ben eath d. d eep
3. a. poor b. t our c. act ual d. gr oup ,
4. a. tiny b. device c. krill d. migrate
5. a.​​ think b. dep th c. fur ther d. brea the
B.​​ Choose the word whose main stress is placed differently from the others.
6 a.​​ maintinsb. marine c. challenge d. device
7. a. investigateb. information c. submarine d. independent
8. a. organism ​​ b. environment​​ c. temperature ​​ d. satellite
9. a. carnivore​​ b. entrapment​​ c. technology ​​ d. Atlantic
10. a. secret​​ b. ocean ​​ c. migra te ​​ d. herbicide ​​ ​​​​

Cho a,b,c là độ dài 3 cạnh của 1 tam giác cm:

a)\(ab+bc+ca\le a^2+b^2+c^2< 2\left(ab+bc+ca\right)\)

b)\(abc\ge\left(a+b-c\right)\left(b+c-a\right)\left(a+c-b\right)\)

c)\(2a^2b^2+2b^2c^2+2c^2a^2-a^4-b^4-c^4>0\)

d)\(a\left(b-c\right)^2+b\left(c-a\right)^2+c\left(a+b\right)^2>a^3+b^3+c^3\)

Cho a,b,c∈R.CM bđt \(a^2+b^2+c^2\ge ab+bc+ca\) (1). Áp dụng cm các bđt sau:

a)\(\left(a+b+c\right)^2\le3\left(a^2+b^2+c^2\right)\)

b)\(\frac{a^2+b^2+c^2}{3}\ge\left(\frac{a+b+c}{3}\right)^2\)

c)\(\left(a+b+c\right)^2\ge3\left(ab+bc+ca\right)\)

d)\(a^4+b^4+c^4\ge abc\left(a+b+c\right)\)

e)\(\frac{a+b+c}{3}\ge\sqrt{\frac{ab+bc+ca}{3}}vớia,b,c>0\)

f)\(a^4+b^4+c^4\ge abc\) nếu a+b+c=1

Cho a,b,c,d>0. CMR nếu \(\frac{a}{b}< 1\) thì \(\frac{a}{b}< \frac{a+c}{b+c}\) (1). Áp dụng cm các bđt sau

a)\(\frac{a}{a+b}+\frac{b}{b+c}+\frac{c}{c+a}< 2\)

b)\(1< \frac{a}{a+b+c}+\frac{b}{b+c+d}+\frac{c}{c+d+a}+\frac{d}{d+a+b}< 2\)

c)\(2< \frac{a+b}{a+b+c}+\frac{b+c}{b+c+d}+\frac{c+d}{c+d+a}+\frac{d+a}{d+a+b}< 3\)

Cho a,b,c,d∈R.CMR a²+b²≥2ab(1) Áp dụng cm các bđt sau:

a)\(a^4+b^4+c^4+d^4\ge4abcd\)

b)\(\left(a^2+1\right)\left(b^2+1\right)\left(c^2+1\right)\ge8abc\)

c) \(\left(a^2+4\right)\left(b^2+4\right)\left(c^2+4\right)\left(d^2+4\right)\ge256abcd\)