英语语法分析

The preferred method is by oxyacetylene flame .

最好采用氧炔焰加热方法。

Oxyacetylene flame can' be used for welding of pipeline.

管道焊接不得使用氧乙炔焰焊接。

Oxyacetylene flame is the hottest one known for ordinary use.

氧炔焰是常规用途中最热的火焰。