Tên nguyên tố	Số hiệu nguyên tử	Số electron lớp ngoài cùng	Kim loại, phi kim hay khí hiếm?
Carbon	6
Sodium	11
Argon	18
Calcium	20

Nguyên tố Y ở chu kì 3 nhóm IVA. Cấu hình electron nguyên tử của Y là

Ở tế bào nhân thực, hoạt động hô hấp xảy ra ở đâu?

Nguyễn Dữ là học trò của ai?

Nguyên tử oxygen có 8 proton, vậy điện tích hạt nhân của nguyên tử này tính theo đơn vị culong là

Nguyên tắc quyền lực nhà nước thuộc về nhân dân trong tổ chức và hoạt động của bộ máy Nhà nước Cộng hoà xã hội chủ nghĩa Việt Nam được thể hiện ở nội dung nào sau đây?

Hoạt động của nền kinh tế có trò kết nối sản xuất với tiêu dùng?

Để xác định phụ nữ có thai hay không, người ta dùng que thử thai để xác định sự có mặt của loại hormone nào sau đây?

Việc làm nào sau đây bị nghiêm cấm trong bầu cử?

Nối tên các văn bản sau đây với sự kiện chính của nó sao cho phù hợp.

WAYS TO IMPROVE YOUR MEMORY

A good memory is often seen as something that comes naturally, and a bad memory as something that cannot be changed, but actually (622) ____________ to improve your memory.

We all remember the things we are interested in and forget the ones that bore us. This no doubt explains the reason why schoolboys remember football results (623) __________ but struggle with dates from their history lessons! Take an active interest in what you want to remember, and (624) ____________ . One way to make yourself more interested is to ask questions — the more the better!

Physical exercise is also important for your memory, because it increases (625) _______________ and sends more oxygen to your brain, and that makes your memory work better. Exercise also reduces stress, (626) _________________.

The old saying that ―eating fish makes you brainy may be true after all. Scientists have discovered that the fats found in fish like tuna, sardines and salmon — as well as in olive oil — help to improve the memory. Vitamin-rich fruits such as oranges, strawberries and red grapes are all good brain food, too.

(Source: ―New Cutting Edge, Cunningham, S. & Moor. 2010. Harlow: Longman)

Câu 624:

Take an active interest in what you want to remember, and (624) ____________ . One way to make yourself more interested is to ask questions — the more the better!

Sau khi thực hiện các câu lệnh sau, mảng A như thế nào?

>>> A = [1, 2, 3, 4, 5]

>>> A. remove(2)

>>> print(A)

Các phát biểu dưới đây là đúng hay sai khi nói về đặc điểm chung của cấp độ tổ chức sống?

Cho phương trình lượng giác \(\text{sin}2x=-\frac{1}{2}\).

Millions of people are using cellphones today. In many places, it is actually considered unusual not to use one. In many countries, cellphones are very popular with young people. They find that the phones are more than a means of communication - having a mobile phone shows that they are cool and connected.

The explosion in mobile phone use around the world has made some health professionals worrieSome doctors are concerned that in the future many people may suffer health problems from the use of mobile phones. In England, there has been a serious debate about this issue. Mobile phone companies are worried about the negative publicity of such ideas. They say that there is no proof that mobile phones are bad for your health.

On the other hand, medical studies have shown changes in the brain cells of some people who use mobile phones. Signs of change in the tissues of the brain and head can be detected with modern scanning equipment. In one case, a traveling salesman had to retire at young age because of serious memory loss. He couldn't remember even simple tasks. He would often forget the name of his own son. This man used to talk on his mobile phone for about six hours a day, every day of his working week, for a couple of years. His family doctor blamed his mobile phone use, but his employer's doctor didn't agree.

What is it that makes mobile phones potentially harmful? The answer is radiation. High-tech machines can detect very small amounts of radiation from mobile phones. Mobile phone companies agree that there is some radiation, but they say the amount is too small to worry about.

As the discussion about their safety continues, it appears that it's best to use mobile phones less often. Use your regular phone if you want to talk for a long time. Use your mobile phone only when you really need it. Mobile phones can be very useful and convenient, especially in emergencies. In the future, mobile phones may have a warning label that says they are bad for your health. So for now, it's wise not to use your mobile phone too often.

What is the word “potentially” in paragraph 4 closest in meaning to?

Trong quá trình thống trị Việt Nam, thực dân Pháp đã dựa vào lực lượng xã hội nào để làm chỗ dựa?

Số cách xếp 5 học sinh ngồi vào một dãy gồm 5 chiếc ghế sao mỗi ghế có đúng một học sinh ngồi là

Phát biểu nào dưới đây sai?

Nguyên tố nào sau đây không phải là nguyên tố vi lượng?