a constant source of annoyance or trouble
una fuente constante de molestia o problema (una fuente constante de molestia o problema)
"The trade dispute has become a thorn in our side."
"La disputa comercial se ha convertido en una espina en nuestro costado." (La disputa comercial se ha convertido en **una espina en nuestro costado**.)
to try very hard to help or please someone
to be more successful than competitors
to find something or someone after a search
to create long-term trust and attachment to a brand
to prepare everything for something to happen
to have a big, broad smile showing happiness