• 四时（four tenses）： 现在时、过去时、将来时、过去将来时
• 四体（four aspects）： ⼀般体、进⾏体、完成体、完成进⾏体
• ⼀般体 进⾏体 完成体 完成进⾏体
• 现在时 do be doing have done have been doing
• 过去时 did be doing had done had been doing
• 将来时 will do will be doing will have done will have been doing
• 过去将来时 would do would be doing would have done would have been doing