Study calculus, the first step is to understand that the "limit" the necessity of introducing: because, the concept of algebra is people are familiar with, but, algebra is unable to process the concept of "unlimited". So in order to use algebraic processing to represent infinite quantities, the concept of "limit" is constructed. In the definition of "limit", we can see that this concept bypasses the problem of dividing a number by 0, and introduces a process with any small amount. Is to say, the divisor is not zero, so meaningful, at the same time, this process can take any small small, as long as meet the Δ range, less than the arbitrary small, we can say he limit to the number, you can think it is opportunistic, however, his practical proof, such a definition is more perfect, the possibility of giving the correct inference. The concept is successful Work, Chinese word, have the verb, the noun two kinds of speech. As a verb, it has operation, operation, operation, etc. This prescription to get succinct and concise can often be misunderstood and requires judicious application. It certainly doesn't imply that mcdougal must make all their sentences short and choppy or leave out all adjectives, adverbs, and qualifiers. Nor should it signify they must avoid or eliminate all detail from the writing and treat her or his subjects only inside the barest skeleton or outline form. But the requirement does signify every word devoted to paper should tell a new challenge towards the reader and contribute in a very significant and non-redundant way on the message that mcdougal is intending to share. Retailers are the ultimate distribution channel. In the face of individual consumer market, it is the distribution channel system