Words are the basic elements of sentences. If we want to improve English in all aspects, vocabulary should count. Native speakers have an estimated vocabulary over 20,000 words. So, after graduation, it does not mean that a learner can come to a halt on the accumulation of new words. We can close to be at the level of native speakers if we keep learning. The mastery of words does not lie in how many ones we memorize from a dictionary. It depends on the frequency of the use of words. Therefore, we authentically master new words till we can freely use them in reading, writing, speaking and listening. It is a lifetime learning. Practice makes perfect.