Already and Yet - Used with the Present Perfect
Both already and yet refer activities around the present moment in time.
I have already finished my lunch.
Have you seen Tom yet?
They haven't visited Rome yet.
Already - Referring To a Past Event
Already is used to something that happened before the moment of speaking. However, it refers to something that affects the present moment in time. Let's take a look at a few examples:
I have already finished the report.
This sentence could be used to express the idea that I finished the report and it is ready to read now.
She has already seen that film.
This sentence might express that the woman saw the film in the past, so she has no desire in the present moment to see the film.
They have already eaten.
This sentence would probably be used to state that they are no longer hungry in the present moment.
The key to using 'already' is to remember that an action that has happened in the past - often in the recent past - affects the present moment or a decision about the present moment in time and therefore is used with the present perfect tense.
Already - Sentence Placement
Already is placed between the auxiliary verb 'have' and the participle form of the verb. It is used in the positive form and should not be used in the negative.
Subject + have / has + already + past participle + objects
I have already seen that film.
Mary has already been to Seattle.
I have seen already that film.
Already is generally not used in the question form. However, when expressing surprise in a rhetorical question it is sometimes used in informal conversations.
Have you already eaten?!
Have you already finished?!
Yet - Asking Questions
Yet is used to check whether something has occurred up to the present moment.
Have you seen that film yet?
Has Tim done his homework yet?
You may notice that there is a similarity to the use of 'ever' in the present perfect to ask a question:
Have you ever seen that film?
Have you seen that film yet?
These questions are very similar in meaning, but yet is generally used to ask about something closer to the present moment. Yet is often used when someone expects something to have occurred recently.
Have you finished that report yet? - In this case a colleague expects the report to be finished soon.
Have you ever finished that repot? - Ever is used to ask about experience in general, not whether something specific has been completed recently.
Yet - Question Placement
Yet is always placed at the end of a question. Notice that yet is not used with question words as questions with yet are yes/no questions.
Have + subject + past participle + objects + yet + ?
Have you finished that report yet?
Has she bought a new car yet?
Yet - Negative Form
Yet is also used in the negative to express that something that is expected has not yet happened. In this case, yet is placed at the end of the sentence.
Subject + have not / has not + past participle + objects + yet
主语+have not/has not+过去分词+宾语+yet
She hasn't finished the report yet.
Doug and Tom haven't telephoned yet.
Already - With the Past Perfect
Already can also be used with the past perfect to express that something had happened before something else. It is used in the same senses explained previously with present perfect usage.
She had already eaten when he arrived.
Jackson had already done his homework when he was asked for help.
Already - With the Future Perfect
Already is also used with the future perfect to express that something will have been completed before something else occurs.
She will have already finished the paperwork before the meeting.
Frank will have already prepared the report by the time the boss asks for it.