to be to [VERB]

1 This type of expression uses a form of the verb to be followed by an infinitive verb with to, for example: you are to call. It's most commonly used to give a very authoritative and categorical command to someone, so it's most often used by parents, bosses, teachers, police, and anyone in  authority. For instance, in this example, the father wants his son home by midnight. Period! No excuses!

You can go out with your friends, but you're to be home by midnight.

It's also used to communicate a command from someone else. For instance, here the speaker is communicating a command given by the boss. He wants them to stay until the report is finished. No exceptions!

The boss says we're to stay here and work on this report until it's finished — even if it takes all night!

It can even be used in the passive. Say you're an investigator at a crime scene directing your team of investigators:

I want pictures of everything, but nothing is to be touched or moved!

In other words, this phrase is used to express that something ABSOLUTELY AND CATEGORICALLY MUST (NOT) be done, so use it wisely or you may sound bossier than you mean to. For instance, when addressing your roommates. The following would only be appropriate to say if your roommates have a history of eating other people's food: 

There's a cake in the refrigerator. It's for my niece's birthday party tomorrow. None of you is to eat it!

_________________________⦿ who all | When you anticipate that the answer to what? who? where? is going to be more than one thing, person, or place, you can use the forms what all? who all? and where all? Note that we use singular is here even though we expect a plural answer. This is because even when we expect more than one person, we would normally ask Who's going?, and this doesn't change when we add all. I believe in Britain they ask Who all are going?⦿ You know what? | Used rhetorically before answering a question, this phrase implies that you were going to respond one way, but thinking about it, decided to go the other way. Here, the dad was instantly going to say no, but upon giving it more thought, he changed his mind and decided to actually say yes for the reasons he gives.

Andy and his friends are planning a weekend camping trip. Andy's not sure his dad will let him go, but he tries his luck.


Andy: Dad, me and the boys are thinking about going on a camping trip this weekend.

Dad: I see. And who all is going?

Andy: Me, Bobby, Alex and Christian.

Dad: No adults?

Andy: No...

Dad: You know what? Yes, you can go. You're a young man now, and at some point, I have to start trusting you. But... you're to call me every morning and every evening to let me know you're ok.

2a A more journalistic usage of this phrase is usually only seen in newspaper headlines. It's used to announce a future event of any kind — something someone is expected to do and basically corresponds to the future expressed by going to. Note that in the journalistic style, the verb to be is often omitted, resulting in headlines like the following:

President Biden to Address the Nation Today

This basically means that the president is going to address the nation today; or is expected to address the nation today, but with is omitted.

2b This form is also used in spoken English in questions using the syntax [QUESTION WORD] [TO BE] [SUBJECT] [INFINITIVE]. For instance, Where am I to go?  or How was I to know? 

In this type of question, to be to means supposed to or expected to: «Where am I expected to go?» or «How was I supposed to know?». It expresses a certain perplexity and frustration on the part of the speaker who sincerely has no idea what to do or what to think in a certain situation. 

Natasha walks into the kitchen and finds her boyfriend eating a piece of cake... the cake she made for her niece's birthday party.


Natasha: Alex, please tell me you're not eating the cake I made for Natalie's birthday!

Alex: How was I to know that cake was for your niece's birthday? I thought it was for everybody!

3 if-Clauses 

The phrase to be to [VERB] is commonly used after if in a hypothetical sense. Here, it expresses a nuance of IF THE PLAN IS FOR [SOMEONE] TO [VERB], THEN... followed by a condition that must be met or a prediction about how things are going to be, etc. 

For instance, in this example, the trainer hasn't decided if he's going to take you on as a client — he has an important condition:

If I'm to be your personal trainer, you have to quit smoking today. Otherwise, I'm not going to waste my time.

Here, the trainer could've also said If I'm GOING TO be... with the same meaning. Using either of these phrases makes it sound more or less like the trainer has already agreed to take the job, but is very serious about his conditions. 

In this usage, the if is sometimes strongly emphasized. For instance, in the following example, the speaker has more or less decided to hire you, but again, under one strong condition:

If you're to work for me, you cannot — under any circumstances — smoke cigarettes. I can't stand the smell.

Let me give you another example. Say you have a catering company, i.e. you provide food and servers for parties and events. You're asked to potentially provide catering for a huge event with over 1000 people at some future point. They still haven't set the date, but they want you to give them a price quote, so they can come up with a budget. You give them a quote and propose a menu, and it's accepted. But you have one condition

If my company is to cater this event, we're going to need at least two weeks' notice. 

This implies that you've already more or less accepted the job, but the only way you'll commit fully is under the condition that they let you know the actual date of the event at least two weeks in advance. 

However, let's say you weren't impressed with their offer and wanted to sound more detached and hypothetical. In that case, instead of if my company is to... you'd simply keep things more vague by using the subjunctive: if my company were to cater this event... This would make it clear that you haven't decided one way or the other and everything is still under discussion; up in the air.

How do you say this in your language? 

It may help others if you translate the snippets into your own native language below. 

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