真正坚固的友谊，经得起时间和距离的考验。

Zhēnzhèng jiāngù de yǒuyì, jīngdeqǐ shíjiān hé jùlí de kǎoyàn.

Truly strong friendships can stand the test of time and distance.

这种材料既轻又坚固，非常适合做飞机零件。

Zhè zhǒng cáiliào jì qīng yòu jiāngù, fēicháng shìhé zuò fēijī língjiàn.

This material is both light and strong, so it is very suitable for making airplane parts.

房子的地基不够坚固，遇到地震就很危险。

Fángzi de dìjī bù gòu jiāngù, yùdào dìzhèn jiù hěn wēixiǎn.

If the foundation of a house is not solid enough, it is very dangerous in an earthquake.