at his leisure

• adv. 当有空的时候(在认为方便的时候)

at his leisure的用法和样例：

例句

1. John is repairing his model plane at his leisure.
   约翰不慌不忙地修理着他的航模。
2. Having disposed of the main opposition, he could polish off the remainder at his leisure.
   由于清除了主要的反对派，他可以从容不迫地收拾掉剩下的对手了。