peak进入了成熟期后(the Maturity Stage)销售量将会到达顶峰(peak)，因为这个时候已经达到产品的饱和度(the saturation point)。

Today we’re going to look at marketing over the lifetime of a product and how the different facets in the product life cycle impact on the kinds of marketing decisions we make and influence the marketing strategy we employ.
Of course, the first stage in the product life cycle is known as the Market Introduction Stage. At this point, costs are very high indeed, and, since the product is fresh to the market, sales volume can be low to start as the product has yet to take off. What the marketing department must do therefore is get as much publicity as possible for the product and begin to develop brand awareness and loyalty. Think of the process as little steps. The first step is to get the brand noticed by your target market. This will require aggressive advertising using mediums which are likely to expose the product to, and, just as importantly, appeal to the target customer. The next step would be to encourage the target market to try the product. Promotions, free trials and other special offers all play a role in new customers over to your brand.
Don’t expect to make money during the Market Introduction Stage. The focus should be solely on creating brand awareness.
Then we move into the Growth phase. Now here costs will reduce dramatically as sales rise and economies of scale in production begin to kick in. Public awareness of the product has increased and the focus of the marketing campaign will now switch more from creating awareness to generating customer loyalty and brand recognition. The first step for the marketing goal is to find a way to reward return customers for their loyalty — in other words, provide them with an incentive to continue coming back.
During the growth phase, several new competitors are likely to emerge as tangible threats to the business. The next step for the marketing team, then, is to differentiate their brand from the term on the market.  Unless customers see your product as distinct from the competitors’, they really have no reason to remain loyal to it; therefore, this brand differentiation that I have just spoken of is vital.
So, you’ve grown your business, now it’s time to sit back and reap the rewards. We’re into the Maturity Stage. During this period, sales will peak as the saturation point is reached.
Competition will be intense, however, the work you have done on developing brand loyalty and differentiating your product from that of competitors’ will really pay off now. The marketing department must continue to differentiate the brand from competitors’, and, if possible, diversify the product features; that is, find new applications for the product in order to open up potential new markets and prolong the Maturity Stage.
The final stage in the product life cycle is Saturation and Decline. Some would argue that reaching this stage is a natural progression for every product. However, there is a growing belief that, should the marketing department do its job properly, the product should stabilise and never really fall into decline. We’ll examine this debate a little more closely next time.