Almost every new innovation goes【C1】______three phases.【C2】______initially【C3】______into t

Almost every new innovation goes【C1】______three phases.【C2】______initially【C3】______into the market, the process of【C4】______is slow. The early models are expensive and hard to use, and perhaps even unsafe. The economic【C5】______is relatively small. The second phase is the explosive one,【C6】______the innovation is rapidly adopted by a large number of people. It gets cheaper and easier to use and becomes something familiar. And then in the third【C7】______,【C8】______of the innovation【C9】______again,【C10】______it permeates out across the economy. During the explosive phase, whole new industries spring up to produce the new product or innovation, and to【C11】______it. For example, during the 1920s, there was【C12】______dramatic acceleration in auto production, from 1.9 million in 1920 to 4.5 million in 1929. This【C13】______was accompanied【C14】______all sorts of other essential activities necessary for an auto-based nation: Roads had to be built for the cars to【C15】______; refineries and oil wells, to provide the gasoline; and garages, to repair【C16】______. Historically, the same【C17】______is repeated again and again with innovations. The construction of the electrical system【C18】______an enormous early investment in generation and distribution【C19】______. The introduction of the radio was followed by a buying spree by Americans that quickly brought radios into almost half of all【C20】______by 1930, up from nearly none in 1924.

【C1】

A．over

B．along

C．through

D．under

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