Definition: to try hard to achieve something Level: B2
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.
