lay：lay,lay,lay
laid：laid,laid,laid
lie：lie,lie,lie
lay：
Lay是动词，表示“放置”、“铺设”或“说”之意，表示主动的意思。它是不及物动词，不需要宾语。它一般用於下列句型：lay +sth.+ adj. + n. (把某物放置在某物上)，lay +sth. + adv.（把某物放置在某种位置），lay +oneself + adv.（将自己放置在某种状态）。例如：
She laid her book on the desk.
He laid his bag behind his chair.
He laid himself on the grass and enjoyed the sunshine.
laid：
Laid是动词lie的过去式，表示“把某物放置在某物上”、“将某物放置到某处”或“将自己放置到某种状态”，是不及物动词，不需要宾语。它一般用於下列句型：laid +sth.+ adj. + n. (把某物放置在某物上)，laid +sth. + adv.（把某物放置在某种位置），laid +oneself + adv.（将自己放置在某种状态）。例如：
She laid her book on the desk.
He laid his bag behind his chair.
He laid himself on the grass and enjoyed the sunshine.
lie：
Lie是动词，表示“将自己放置在某处”或“久留某处的状态”之意，它一般用於下列句型：lie + on/in/under/underneath + n. (将自己放置在某物上)，lie + to + n. (将自己放置在某位置)，lie + adv. (久留某种位置)，lie +on +sth. (久留某物上)，lie +between+ n. (久留某物之间)，lie +against + n. (久留某物上)。例如：
She lay on the couch and took a nap.
He lies in the sun to get a tan.
The river lies between two mountains.