【一】grew heads 长有脑袋

【二】We were a lot easier to watch.【主语(we)为后面不定式(to watch)的逻辑宾语】

=To watch us is a lot easier.=It is a lot easier for her to watch us.

Mom says we were a lot easier to watch before we grew heads.【before 为连词引导时间状语从句作时间状语】

=Mom says it's a lot easier for her to watch us before we grew heads.【before 时间状语从句作时间状语】

=Moms says(that) to watch us before we grew heads is a lot easier.【before 引导时间状语从句作时间状语】

参考译文：妈妈说在我们长有脑袋之前看护我们要更加容易的多。

备注：before we grew heads为时间状语从句作动词不定式(to watch us)的时间状语】

My parents left us with a babysitter last night. When they got home, eighty-seven of us were stuck to a strip of flypaper. Mom said we were a lot easier to watch before we grew heads.

参考译文：我的父母昨晚把我们委托/交托给保姆照看，当他们回到家的时候，我们中有七到八个都被困在一张捕蝇纸动弹不了。妈妈说在我们长有脑袋之前看护我们要更加容易的多。