阅读下列短文，从每题所给的四个选项（A、B、C和D）中，选出最佳选项。

    There are many useful suggestions that can help one to improve English. Here are some of them to increase one's English language vocabulary.

    Learning English vocabulary is about much more than just learning the right words. It is based on understanding important words and expressions.

    Learning a word will not help very much if you quickly forget it. Researches show that it takes from 10 to 20 repetitions(重复) to really make a word part of your vocabulary. Since most words are learned from how they are used in context (上下文), the more words one is shown, the better vocabulary one will have. Keep a piece of paper close to you. When you read, pay close attention to the word you do not know, write the word down and try to understand its meaning from the context. Then look up the word in a dictionary. 

    Remember that if you do not use English words that you have just learned in conversation or writing, you will forget them very quickly. So the best way to learn new words effectively is just by trying to use them in conversation and writing. Remember also that practice is the key to fluent spoken English.

    Building vocabulary is a life-long task. Remember: ＂In the beginning was the word.＂ Your future could depend on how rich your vocabulary is. It will also determine the quality of your communication.

    You carry a 1.3 kg mass of fatty material in your head that controls everything you will ever do. This fantastic control center lets you think, learn, create, and feel emotions. It also controls everything your body does. What is this amazing machine? It's your brain — a structure so amazing that the famous scientist James Watson called it ＂the most complex thing we have yet discovered in our universe＂.

    Imagine your kitten jumped onto the kitchen counter, and was about to step onto a hot stove. You would have only seconds to act. In situations like this, your brain reads the signals from your eyes and quickly calculates when, where and at what speed you need to run to save her. Then it tells your muscles to move. No computer can match your brain's great ability to download, process, and react to the flood of information from your eyes, ears and other sensory organs.

    If a bee lands on your foot, sensory neurons(神经元) in your skin send this information to your brain at a speed of more than 240 kilometers per hour. Your brain then uses motor neurons to send a message back to your foot: Shake the bee off quickly! Motor neurons can send this information at more than 320 kilometers per hour!

    Your brain contains about 100 billion tiny cells: neurons — it would take you more than 3,000 years if you tried to count them all. Whenever you dream, laugh, think, see or move, tiny chemical and electrical signals are racing between these neurons along billions of tiny neuron pathways. Believe it or not, the activity in your brain never stops. Countless messages fly around inside it every second, like a super-fast game of table tennis. Your neurons create and send more messages than all the phones in the entire world. And although a single neuron generates only a tiny amount of electricity, all your neurons together can generate enough electricity to power a light bulb.