– 她以前很喜欢你。tā yǐqián hěn xǐhuān nǐ. She used to like you a lot before. – 我一个月以前回来了。wǒ yīgè yuè yǐqián huí lái le. I came back a month ago. – 吃饭以前，你应该洗手。chīfàn yǐqián, nǐ yīnggāi xǐshǒu You should wash your hands before eating.