I’ve already had lunch. ^{现在完成时(强调已经完成了某事)}

already ^{adv. 已经(肯定句、疑问句)(通常不会用于否定句中)}

• He has already had a bath. ^{（already通常在 done 前）}他已经洗完澡了。
• I have already had my lesson. ^{我已经上完课了。}
• Have you already done your homework? ^{你已经完成作业了吗？}
• Has he already had a swim? ^{他已经游完泳了吗？}

上列句子中，不使用“already”一样的可以表示已经完成^{（already表强调）}，某个时间点做某事的全部完成而不是部分完成。

I had lunch at half past twelve. ^{一般过去时（在某个时间点做过某事）}

• I had a whole pizza to myself. ^{我独自吃了一整个比萨饼。}
• We had a meal in a restaurant. ^{我们在餐厅吃了顿饭。}
• You had your chance and you blew it. ^{你本来有机会，却没有抓住。}
• She had short, wavy brown hair. ^{她有一头又短又卷的褐发。}

Have  a cup of coffee then.

just adv. ^{刚刚（肯定句）（ 通常在 have\has 的后面）}

• He has just had a bath. ^{后他刚刚洗完澡。}
• I have just had my lesson. ^{我刚刚上完课。}

Aren’t you lucky! ^{（否定疑问句）}

• Are you lucky? ^{你幸运吗?}
• Aren’t you lucky? ^{难道你不幸运吗？}
• You are so lucky！^{你可真幸运啊！}