leisure(d)
1.at leisure和at one's leisure不同。at leisure有时用作状语短语，有时用作形容词短语。at one's leisure只用作状语短语，不用作形容词短语。at leisure用作形容词短语作“有空的”解，后面有时接不定式。例如：I am at leisure. 和I am at leisure to chat with you. at leisure用作状语短语作“从容地”解。例如：We may proceed at leisure. at one's leisure作“在有空的时候”解。例如：Please call on me at your leisure.
2.说“有闲阶级”用leisure class和leisured class都可以。
3.He has (the) leisure to read fiction里的the可有可无。
