on the earth 在地球上，作地点状语，位于句首或句末。on earth 究竟，到底。用于疑问句或副词后，加强语气。

All the living things {#blank#}1{#/blank#} depend on the sun. 地球上所有的生物都依靠太阳。

What {#blank#}2{#/blank#}do you mean? 你到底是什么意思？

Singapore is an English-speaking country, so it's also a good place {#blank#}1{#/blank#} {#blank#}2{#/blank#} your English!

My uncle{#blank#}1{#/blank#}his hometown for quite a few years.

Please {#blank#}1{#/blank#} {#blank#}2{#/blank#} your birthday plan.