to the best of your knowledge/belief/ability etcTHINK SO/NOT BE SURECANused to say that something is as much as you know, believe, or are able to do 就某人所知/在某人看来/尽某人所能等 I’m sure he’ll do the work to the best of his ability. 我相信他会尽己所能做好这项工作。
→ to the best of your knowledge/belief/ability etc at best3(4)