Mệnh đề nào sau đây đúng?

Loại nông phẩm nào thường được phơi khô để giảm cường độ hô hấp trong quá trình bảo quản?

I-li-at và Ô-đi-xê là bản anh hùng ca nỗi tiếng của nước nào thời cô đại?

1. Do you find yourself yawning all day at school? You probably need more sleep. However, it is not just how much sleep you get that is important. What you do before bedtime also has a huge effect on how you feel the next day. If you spend time chatting to someone on social media, or reading a book on your e- reader, you are not alone.

2. All devices' screens give out a large amount of blue light, which affects the body's production of the sleep hormone, melatonin, which can change your sleep patterns. So it is not just getting to sleep that becomes hard, but the quality of your sleep also suffers. The result is that you can wake up several times during the night, and have difficulty getting up in the morning.

3. Sleep is food for the brain, so not sleeping well can be a severe problem for anyone, especially for teenagers, because their brains are still developing. When you do not sleep well, it can be difficult to concentrate at school, which makes it harder to learn and get good grades. It can also affect your mood, making you feel sad or anxious.   

4. So, it is clear you should not use your phone before you go to sleep. Why not leave it in another room? Nothing on social media is so important that it cannot wait a few hours! You should rediscover paper books and enjoy feeling tired and sleepy before bedtime rather than wondering why your best friend has not liked your photo! How will you wake up? You do not have to use the alarm on your phone. Go and buy yourself an old-fashioned alarm clock! The negative effects that screen time is having on sleep have been in the news a lot recently, so manufacturers of smartphones and tablets have added a feature to the mobile devices that can help reduce these. Most new phones have a night-time setting that changes the colour of the screen so that it gives out less blue light. If you really cannot avoid going onto social media at bedtime, think about turning on this setting on your phone.

What is the word “severe” in paragraph 3 is closest in meaning to?

Một tạp chí bán được 25 nghìn đồng một cuốn tạp chí. Chi phí xuất bản \(x\) cuốn tạp chí được cho bởi công thức: \(\mathrm{C}(x)=0,0001 x^{2}-0,2 x+11000\) vạn đồng (bao gồm: lương cán bộ,công nhân viên, \(\ldots\) ).

Chi phí phát hành cho mỗi cuốn là 6000 đồng. Các khoản thu chi bán tạp chí bao gồm tiền bán tạp chí và 100 triệu đồng nhận được từ quảng cáo. Giả sử số cuốn in ra được bán hết. Tính số tiền lãi lớn nhất có thể có được khi bán tạp chí (làm tròn đến chữ số hàng chục nghìn)

Đường cong trong hình vẽ là đồ thị của hàm số nào trong các hàm số sau đây?

Mỗi cảnh mới trong dự án video trên Animiz gồm?

Dãy số \(\left( {{u_n}} \right)\) nào sau đây là dãy số giảm?

Để quan sát được hình dạng kích thước của tế bào thực vật, cần sử dụng dụng cụ nào sau đây?

Cho tập hợp P = {1; 3} và tập hợp Q = {3; x}. Giá trị của x để P = Q là:

Cho hai mệnh đề: $P$: "$30$ không chia hết cho $5$" và $Q$: "$\pi < 3,15$". Khẳng định nào sau đây đúng?

Chọn ý đúng: Theo em vai trò của ngành bưu chính viễn thông đối với phát triển kinh tế là?

Hệ thống nào có nhiệm vụ đảm bảo an toàn giao thông khi trời tối?

Read the following passage about human life expectancy 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 23 to 30. 

An engine is a machine that creates mechanical motion from energy. In order to do this, an engine frequently requires some type of fuel to burn. Nowadays, many engines are used to power cars and other forms of transportation. These vehicles most commonly have an internal combustion engine and rely upon gasoline for power. However, there are several types of engines that can use alternative energy sources. Many people are trying to switch to them because gasoline, which is a fossil fuel, creates pollution and is also a non-renewable resource.

These days, engines that are able to burn biofuels are somewhat common. Biofuels are fuels that are made from biological material, such as corn, soybeans, and sugarcane. These biofuels burn cleanly, so they produce much less pollution than fossil fuels. In some countries, such as Brazil, cars with biofuel engines are standard. In fact, most of the cars in Brazil have engines that can operate on either gasoline or biofuel.

A second type of alternative engine is the electric engine. Cars with electric engines have been common for decades. Most are being used in hybrid cars at the moment. These are vehicles that have both a gasoline-powered engine and an electric one. In many cases, the gasoline-powered engine is used to operate the car at high speeds on expressways. The electric engine is utilised for city driving. One benefit of hybrid cars is that as the gasoline-powered engine runs, it simultaneously recharges the electric engine.

A third type of alternative engine is the hydrogen engine. It utilises hydrogen fuel cells, which convert hydrogen into electricity that can power the car These days, there are many cars and buses that rely upon hydrogen engines. However, there are some problems associated with this type of engine. The hydrogen used in the engine must be processed from other materials, and it is also difficult to store. As a result, vehicles that run on hydrogen are expensive.

Alternative energy sources create less pollution and are often renewable sources of energy. It is hoped that more and more innovations help the use of alternative energy sources become easier and easier.

The author uses corn, soybeans, and sugarcane as examples of _______.

Đâu là ngôn ngữ chính của nhân dân 13 thuộc địa Anh ở Bắc Mĩ?

Khoá ngoài có tác dụng?

Tìm nghiệm của phương trình \(\cot \left( {x - \dfrac{\pi }{3}} \right) = \dfrac{{\sqrt 3 }}{3}\)?

Cho các chất sau: CH₃NH₂, CH₃NHCH₃, (CH₃)₃N, CH₃CH₂NH₂. Số chất thuộc loại amin bậc I?

Cho hàm số \(y=f\left( x \right)\) có bảng biến thiên như sau: