Mạch điện gồm cuộn dây mắc nối tiếp với tụ điện C. Đặt vào hai đầu đoạn mạch điện áp xoay chiều u   =   200 cos ( 100 π t   +   π 12 )   ( V ) thì điện áp giữa hai đầu cuộn dây và hai đầu tụ điện có cùng giá trị hiệu dụng nhưng lệch pha nhau 120 o . Biểu thức điện áp giữa hai đầu cuộn dây là

A. u cd = 100 2 cos ( 100 π t + π 3 ) ( V )  

B.  u cd = 200 cos ( 100 π t + π 6 ) ( V )

C.  u cd = 200 cos ( 100 π t + π 3 ) ( V )

D.  u cd = 200 cos ( 100 π t + 5 π 12 ) ( V )

Đối với đất hình thành tại chỗ, tầng nào là tầng bề mặt trên cùng của phẫu diện đất?

A. Tầng tích tụ sản phẩm rửa trôi

B. Tầng rửa trôi

C. Tầng thảm mục

D. Tầng mẫu chất

Thu gọn các biểu thức sau:

A = \(\left|x^2+2\right|+\left|-3x^2-2\right|-\left|-2x^2-2\right|\)

B = \(\left|2x-3\right|-\left|3x-2\right|-\left|4-2x\right|\) với x > 5

C = \(\left|3x-6\right|+\left|3x+10\right|\) với -2 < x < 2

D = \(\left|8-3x\right|+\left|x+2\right|\) với x < 2

E = \(\left|x-2\right|+\left|x-4\right|+\left|x-6\right|\) với x < 5

F = \(\left|\left(x-2\right)\left(x-4\right)\right|-\left|\left(4-x\right)\left(x-2\right)\right|\)

- Tiêu diệt một bộ phận quan trọng sinh lực địch.

- Khai thông biên giới Việt - Trung.

- Củng cố và mở rộng căn cứ địa Việt - Bắc.

Đó là ba mục đích trong chiến dịch nào của ta?

A. Chiến dịch Việt Bắc thu đông 1947.

B. Chiến dịch Biên giới thu đông 1950.

C. Chiến dịch Hoà Bình - Tây Bắc - Thượng Lào.

D. Câu A và B đúng.

Nguyên tử hiđrô gồm một hạt nhân và một êlectrôn quay xung quanh nó. Lực tương tác giữa êlectrôn và hạt nhân là lực tương tác điện (lực Culông). Tốc độ của êlectrôn khi nó chuyển động trên quỹ đạo có bán kính  r 0 = 5 , 3 . 10 - 11 m  (quỹ đạo K) là?

A. 2,18. 10 6 m / s

B. 2,18. 10 6 m / s

C. 2,18. 10 5 m / s

D. 2,18. 10 7 m / s

Ngày nay, chúng ta dự báo được khá chính xác về quá trình hình thành và hướng di chuyển của bão là nhờ vào

A. công nghiệp hoá, hiện đại hoá.

B. hội nhập toàn cầu.

C. các thiết bị vệ tinh khí tượng.

D. nâng cao dân trí.

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the question.

         One of the factors contributing to the intense nature of twenty-first-century stress is our continual exposure to media – particularly to an overabundance of news. If you feel stressed out by the news, you are far from alone. Yet somehow many of us seem unable to prevent ourselves from tuning in to an extreme degree.

         The further back we go in human history, the longer news took to travel from place to place, and the less news we had of distant people and lands altogether. The printing press obviously changed all that, as did every subsequent development in transportation and telecommunication.

         When television came along, it proliferated like a poplulation of rabbits. In 1950, there were 100,000 television sets in North American homes; one year later there were more then a million. Today, it’s not unusual for a home to have three or more television sets, each with cable access to perhaps over a hundred channels. News is the subject of many of those channels, and on several of them it runs 24 hours a day.

        What’s more, after the traumatic events of Sptember 11, 2001, live newcasts were paired with perennial text crawls across the bottom of the screen – so that viewers could stay abreast of every story all the time.

        Needless to say, the news that is reported to us is not good news, but rather disturbing images and sound bytes alluding to diasater (natural and man-made), upheaval, crime, scandal, war, and the like. Compounding the proplem is that when actual breaking news is scarce, most broadcasts fill in with waistline, hairline, or very existence in the future. This variety of story tends to treat with equal alarm a potentially lethal flu outbreak and the bogus claims of a wrinkle cream that overpromises smooth skin.

       Are humans meant to be able to process so much trauma – not to mention so much overblown anticipation of potetial trauma – at once? The human brain, remember, is programmed to slip into alarm mode when danger looms. Danger looms for someone, somewhere at every moment. Exposing ourslves to such input without respite and without perspective cannot be anything other than a source of chronic stress.

(Extracted from The Complete Idiot’s Guide to Beating Stress by Arlene Matthew Uhl – Penguin Group 2006)

According to the passage, which of the following has contributed to the intense nature of twenty-first-century stress?

A. An overabundance of special news

B. The degree to which stress affects our life

C. Our inability to control ourselves

D. Our continual exposure to the media

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 45 to 54.

When most people hear the term “National Park”, they automatically think of names
such as “Yellowstone”, or “Yosemite”, or “Grand Canyon”. The big parks’ names bring to mind vast stretches of undisturbed wilderness perfect for hiking, camping, and naturewatching. But while this vision of America’s National Parks is wholly accurate and sufficiently
breathtaking, there’s more.

America’s National Park system has an incredible 388 places to visit. This number includes not only the big parks, but also monuments, historical sites, recreation areas, battlefields, as well as scenic lakeshores, seashores, and rivers. And the Parks themselves don’t just stop at geyser-fields and mule-excursions. In America’s National Parks, you can climb an active volcano in Hawaii, “spelunk” the vast underground world of Mammoth Cave in Kentucky, dive the exotic coral reef of Biscayne Bay in Florida, or cast your fishing nets in the far reaches of the Pacific with the locals of American Samoa. Each of these 388 places has a unique appeal- from the natural to the manmade, from the ethereal to the factual, from the subtle to the overwhelming – with the whole collection offering vacationers a nearly endless range of interests and activities in which to explore and indulge.

SeeAmerica.org is a great place to begin planning your trip to one of, or several of, America’s National Parks. From the homepage, you can search all of the parks by name, region, activity, or even zip code. The site also serves as a portal to other important sites, like the National Park Service’s official website, www.nps.gov, and the National Park Foundation’s, www.nationalparks.org. From SeeAmerica.org, you can get to all the
information you’ll need to plan your trip from start to finish – from directions to the park, to park fees, to typical weather conditions.

What is NOT true about SeeAmerica.org?

A. It is linked to other useful websites. 

B. You can search some of the national parks by zip code. 

C. It gives you all the information needed. 

D. It is a good guide to help you plan the trip.

Rewrite each of the following sentences. Keep the meaning the same

1. What a funny story!

How............................!

2. My brother could ride a bike when he was 6 years old

My brother ....................... when he was 6 years old

3. We might create a home robot that can do housework in 2030

We will ............................... in 2030

4. Learning English is interesting

It is ..............................