It's more practical to use aluminum for aircraft building it's cheap, strong, and machinable while titanium is expensive and isn't easy to get despite being the seventh most common metal on Earth.

使用铝来制造飞机更为实用，因为它便宜、坚固且易于加工， 而钛则昂贵且不易获得， 尽管它是地球上第七种最常见的金属。