engine

翻译：

In the last few years,the investment is the engine of Chinese economy,mow it is the consumption.

改正：

In the past few years, China's economy  was driven mainly by investment, whereas today its engine is consumption. 

例句两点：whereas  drive by

场景：口语曾经是他找工作的障碍，现在却成了他的晋升利器

Spoken English which was once an obstacle to his employment becomes an engine of his job promotion.