review of must

Hi there, students. In this video, I am going to make a brief review of the use of must. Ok, we can use 'must ' for logical certainty. For example, he must be here, ok. That's talking about a logical certainty in the present. Ok, he must have been here, ok, that's a logical certainty in the past. He must be here, his wife is here; he must have been here, there is a photo of him in the garden. Ok, so in both of these, it is a logical certainty that he is here now or he was here in the past he must be here, he must have been here. But notice we can't use this in the future, ok. This only talks about prsent or past. And then in the negative, oh, he mustn't have been here. Ok, we can use this in a logical certainty saying 'it is impossible that he is here now', he mustn't be here. But personally I would use 'he can't be here', it's impossible for him to be here. It's possible again, if his wife says he didn't come, then he mustn't have been here. It's possible, but again, I would use in this case 'couldn't'. So for logical certainty negative , something your certainty isn't true, I would recommand 'can't ' for a present and 'could' for a past. Ok, now we can use must for necessity. For example, you must buy a ticket to ride on the train. Ok, here this is talking about either present or near future, you must pass the exam to enter the university, yeah. And in the past, I think  I would use 'had to', so for example, you had to buy a ticket to get into the concert And necessity in the past not using must. Ok, so you had to buy, yeah. Ok, now also we use must to talk about strong recommendations. You must lose weight or you are going to be very ill. This is a very strong recommendation. Here is talking about the present or the near future. Ok, you must lose weight and then in the negative, you mustn't lose weight, again, it's a strong recommandation, almost like a prohibition. You mustn't lose weight or you are going to get more weight or you are going to be very ill. To talk about strong recommendations in the past, or even just weak recommendations, I would use should. So you should use should. Yeah. So He should have lost weight or he shouldn't have lost weight. This is well, talking about recommendations for things in the past, hindsight with 20/20 vision. Ok, that's a (compl ...??). But let's see, for recommendations, ok, you must do this, you mustn't do that, and in the past, you should have done this or you should have done that. Ok, finally let's look at 'must' for prohibition. You mustn't work on the grass, ok, this is talking about the present or the nea future again, or even habit. Ok, something that is prohibited. And then in the past for this prohibition, I would say 'you couldn't work on the grass'. When I was at university, you couldn't work on the grass. So notice for this prohibition, mustn't for present and near future, but couldn't for the past, ok. Anyway I hope that clear some of your doubts, I am sure there are lots more, because these modal verbs are really (complics?), with different meanings, different uses in different tenses. But persevere with them, and you will find them easier. Ok anyway, if you enjoy this video, give it a rating; subscribe to my channel and I will see you soon. Bye for now.


各位！在這個錄像裡，我會將must的用法做一個簡要的回顧。我­們可以用must表示邏輯上的確定性。比如說，他一定要來這裡，­這個must就是在將邏輯上的確定性。他一定已經來過這了，這句­表示的是在過去的邏輯上的確定性。他一定在這，因為他的妻子在這­裡。他一定來過這裡，因為在花園裡有他的一張照片。這兩個例子都­是在說邏輯上的確定性，一個是說現在，另一說的是過去。他一定在­這裡，他一定來過這裡。要注意，我們不能將must用在將來時態­中。因為must僅能用在現在和過去兩種時態中。在否定句中，他­一定沒有來過這裡，我們可以用must表達邏輯上的現在不可能性­，he mustn't be here, 但是我個人傾向於用can't，he can't be here，他是不可能在這裡的。在類似的使用上，he mustn't havee been here, 有這個可能性，如果他的妻子說他沒有來過這裡，那他he mustn't have been here，再說一次，用mustn't 是可以的，但是我會用couldn't, 對於確定性的否定，對某件事你肯定是錯的，我建議現在式用can't, 過去式用couldn't。我們也可以用must來表示必要性。­比如，乘坐火車，你必需購買火車票。這裡是來說現在或者比較近的­將來。升入大學，你必須通過考試才行。對於過去，我認為我自己會­用had to，你had to 買一張票才能進入音樂會。對於談到過去式的必要性，我們一般不用­must,而是用had to。我們也用must來表示非常強烈的建議。你必須減肥，否則­你會病得很厲害。這是非常強的建議。這裡所談論的是目前和較近的­將來。you must lose weight，在否定式中，用you mustn't lose weight。都是非常強烈的建議，近乎命令。你不減肥，或者增­肥，你會得重病。如果談到在過去式中用到建議，或者是較弱的建議­，我建議使用should, he should have lost weight,或者he shouldn't have lost weight。這裡所講的是在過去式中使用建議，hindsig­ht with 20/20 vision，馬後炮的20/20視野節目，哈哈。對於建議來說，用you must do this, you mustn't do that; 對於過去式，用should, you should have done this, you shouldn't have done that。最後我們看看must被用在禁止做某事上的用法。yo­u mustn't work on the grass, 你不可以在草地上做。這句說的是現在或者比較近的將來時態，甚至­是一種習慣，總之是被禁止的。如果是要講在過去的禁令，我會這樣­說：you couldn't work on the grass。在大學裡，你不可以在草坪上工作。在表示禁令的句子­中，用mustn't 表示現在和較近的將來，用couldn't 表示過去的禁令。我希望我已經消除了你們的一些疑問，但是我十分­清楚還有很多你們會感到困惑的地方，因為這些情態詞十分（？），­在不同時態中有不同的意思和用法。但是如果你堅持學習，你會較容­易發現它們。如果你喜歡這個錄像，留下一個‘喜歡’的評級；訂閱­我的頻道，我將很快和你又見面。