如果你想掌握一项技能，就必须每天为之努力。

If you want to master a skill, you have to ___work ___at it every day.

这支队伍持续努力加强他们的防守。

The team continues to ___work ___at strengthening their defence.

良好的关系不会凭空出现；你必须努力经营。

Good relationships don't just happen; you have to ___work ___at them.