engine

翻译：过去几年投资是中国经济的引擎，现在主要是消费在拉动中国经济。

Over the past few years，investment was an engine of the Chinese economy，mainly now the consumption is an engine of it.

参考翻译：While investment was the engine of China's economy a few years ago, today it's mainly driven by consumption. 或 In the past few years, China's economy was driven mainly by investment, whereas today its engine is consumption.

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engine 常可以用来表示“可以引发巨大改变的事物”“带动发展的事物”比如微信就是腾讯的 engine。