Tại La mã, nhà nước điển hình là 

Một máy tạo rung được sử dụng để tạo ra sóng trên dây.

Tần số của máy tạo rung là 60Hz. Khi đó, vận tốc sóng truyền truyên dây là:

Biết hiệu điện thế U_NM = 20 V. Hỏi đẳng thức nào dưới đây chắc chắn đúng?

Read the following passage about education in Nepal and mark the letter A, B, C or D on your answer sheet to indicate the best answer to each of the following questions from 31 to 40. 

Fashion in the 1960s reflected the cultural and political upheaval of the time. The hippie and counterculture movement gave rise to accessories like Pocahontas-style headbands and medallions worn around the neck. Hippies wore long, loosely fitting clothing, often in natural fabrics. Hemlines rose as Mary Quant popularized the miniskirt and hot pants in her lines for JC Penney. And mod fashion, with brightly colored space-age geometric patterns, shift dresses and colored tights became the mainstream. Both miniskirts and mod-shift dresses were worn with knee-high go-go boots.

[A] During the 1970s, the loose-fitting hippie clothes of the prior decade gave way to exotic fabrics and bell-bottom jeans for men and women. Hemlines continued to rise and hot pants continued their popularity, reflecting the flashy style of the decade. However, the 1970s also saw the popularity of a longer hemline, from mid-calf to ankle-length. [B] Women wore peasant-style clothing, especially blouses with off-the-shoulder necklines and lace trim, with their jeans or skirts. [C] Disco fashion emerged, featuring bright patterns and tightly fitting clothing meant to show off the body. Platform shoes elevated their wearer, male or female, anywhere from two to four inches or more. [D]

The 1980s saw another fashion upheaval. Angst-ridden punks wore Dr. Marten and steel-toed army boots, chains, tartan patterns, and bondage pants. Punks focused more on their hair during this period, dying, teasing and chopping their hair into asymmetric styles that seemed to defy gravity. Women—and men—experimented with heavy eyeliner in a variety of colors. Women wore neon colors, jelly shoes, tight jeans, leggings, leg warmers and oversized sweatshirts. Menswear-inspired looks also became popular for both sexes. Men wore ‘power suits,’ named so for their price, which made these suits a reflection of the wealth of the wearer. Women’s jackets featured big shoulder pads that made the shoulders appear higher and larger, similar to the male silhouette.

1990’s fashion was far more subdued than the garish, wild styles of the 1980s. Bands like Nirvana influenced the grunge look, which featured rock-concert tee shirts under plaid flannel shirts, jeans and long, greasy hair. Overalls were worn by both sexes, either with one or both shoulder straps unhooked. The punk style of the 1870s and 1980s evolved into the goth fashion trend, which featured black clothing, black boots and studded bracelets in the style of bands like Nine Inch Nails and Marilyn Manson.

Where does the following sentence best fit?

Embroidered clothing became especially popular with this trend.

Cho biết alen D quy định cây thân cao trội hoàn toàn so với alen d quy định cây thân thấp. Theo lí thuyết, phép lai giữa các cây có kiểu gen nào sau đây tạo ra đời con có 2 loại kiểu hình?

Những đại diện nào sử dụng hình thức dinh dưỡng hóa tự dưỡng?

1) Vi khuẩn nitrate hóa                                            2) Nấm men

3) Vi khuẩn lam                                                       4) Trùng roi

5) Vi khuẩn oxy hóa hydrogen

Read the passage below and choose A, B, C or D.

Although noise, commonly defined as unwanted sound, is a widely recognized form of pollution, it is very difficult to measure because the discomfort experienced by different individuals is highly subjective and, therefore, variable. Exposure to lower levels of noise may be slightly irritating, whereas exposure to higher levels may actually cause hearing loss. Particularly in congested urban areas, the noise produced as a by-product of our advancing technology causes physical and psychological harm, and detracts from the quality of life for those who are exposed to it.

Unlike the eyes, which can be covered by the eyelids against strong light, the ear has no lid, and is, therefore, always open and vulnerable; noise penetrates without protection. Noise causes effects that the hearer cannot control and to which the body never becomes  accustomed. Loud noises instinctively signal danger to any organism with a hearing mechanism, including human beings. In response, heartbeat and respiration accelerate, blood vessels constrict, the skin pales, and muscles tense. In fact, there is a general increase in functioning brought about by the flow of adrenaline released in response to fear, and some of these responses persist even longer than the noise, occasionally as long as thirty minutes after the sound has ceased.

Because noise is unavoidable in a complex, industrial society, we are constantly responding in the same way that we would respond to danger. Recently, researchers have concluded that noise and our response may be much more than an annoyance. It may be a serious threat to physical and psychological health and well-being, causing damage not only to the ear and brain but also to the heart and stomach. We have long known that hearing loss is America's number one nonfatal health problem, but now we are learning that some of us with heart disease and ulcers may be victims of noise as well. Fetuses exposed to noise tend to be overactive, they cry easily, and they are more sensitive to gastrointestinal problems after birth. In addition, the psychic effect of noise is very important. Nervousness, irritability, tension, and anxiety increase affecting the quality of rest during sleep, and the efficiency of activities during waking hours, as well as the way that we interact with each other.

Based on the passage, how does noise affect psychological and physical health in industrial societies?

Kiểu khí hậu nào sau đây làm cho miền Tây Trung Quốc có nhiều hoang mạc, bán hoang mạc?

Văn hóa Ấn Độ trở thành nguồn cảm hứng không chỉ trong nước mà nó còn lan một số nơi khác trên thế giới, tiêu biểu là ở khu vực:

Thông tin của thị trường mang lại người mua điều gì?

Việc các nhà phân phối hàng hóa mua, trữ hàng và bán lại cho các đại lí hoặc nhà bán lẻ giúp lưu thông hàng hóa hiệu quả thể hiện đặc điểm của chủ thể nào trong nền kinh tế?

Bài thơ Thu điếu được Nguyễn Khuyến sáng tác trong thời gian nào?

Em hãy nêu khái niệm của Sử học?

Một vật dao động điều hòa với biên độ \(A\) và chu kì \(T\). Trong khoảng thời gian \(\Delta t = 4T/3\), quãng đường lớn nhất \(\left( {{S_{\max }}} \right)\) mà vật đi được là:

Read the passage below and choose A, B, C or D to fill in each blank.

In Part Three of the Speaking Section you work together with a partner. You have to do a single task which usually lasts about 3 minutes. One possible task is “problem solving”, which means you have to look at some visual information and then discuss the problem with your partner. You may be shown photos, drawings, diagrams, maps, plans, advertisements or computer graphics and it  is essential that everyone (631)___________ them carefully. If necessary, check you know exactly (632) ________________ the examiner to repeat the (633) __________ or make them clearer.

While you are doing the task, the examiner will probably say very little and you should ask your partner questions and (634)  ___________ suggestions if he or she is not saying much. If either of you have any real difficulties, the examiner may decide to step in and help. Normally, however, you find plenty to say, which helps the assessor to give you a fair mark. (635) ____________in doing the task by competing with your partner, which includes taking turns in giving opinions and replying appropriately, although in the end it may be possible to “agree to disagree”.

Miền nghiệm của bất phương trình: \(3x + 2\left( {y + 3} \right) \ge 4\left( {x + 1} \right) - y + 3\) là mặt phẳng chứa điểm. 

Mâu thuẫn giữa các nước đế quốc “già” và các nước đế quốc “trẻ” cuối thế kỉ XIX - đầu thế kỉ XX chủ yếu là:

Dòng hỗn hợp khí (gồm \(80,3\%{{\text{N}}_{2}};11,5\%{{\text{O}}_{2}}\); còn lại là \(\text{S}{{\text{O}}_{2}}\) theo thể tích) ở \({{427}^{\circ }}\text{C}\) và \(1,0\text{ }\!\!~\!\!\text{ atm}\) được dẫn vào lò phản ứng 2 (thiết bị số 2) với tốc độ v (\({{\text{m}}^{3}}/\) giờ\()\). Biết rằng hiệu suất phản ứng tạo thành sulfur trioxide ở lò phản ứng 2 là \(80\text{ }\!\!%\!\!\text{ }\) và nước được dẫn vào thiết bị số 4 với tốc độ \(0,144\text{ }\!\!~\!\!\text{ }{{\text{m}}^{3}}/\) giờ. Hãy tính tốc độ dòng hỗn hợp khí \(v\) (theo \({{\text{m}}^{3}}/\) giờ) cần dẫn vào thiết bị số 2 để thu được \({{\text{H}}_{2}}\text{S}{{\text{O}}_{4}}98\text{ }\!\!%\!\!\text{ }\) ở thiết bị số 4. Giả thiết các khí là khí lý tưởng. Hằng số khí \(\text{R}=0,082\) lít.atm/mol.K, khối lượng riêng của nước \(\text{d}=1,0\text{ }\!\!~\!\!\text{ g}/\text{c}{{\text{m}}^{3}}\), khối lượng nguyên tử \(\text{H}:1;\text{O}:16,\text{ }\!\!~\!\!\text{ S}:32\).

Chọn phương án đúng: Có mấy chất dinh dưỡng chính trong phân bón?