Introduction
We find to be to + infinitive to discuss official arrangements, orders or official instructions.
This structure has both active and passive form.
We use the active form when we are expecting something to happen (for pre-conditions).
Form
For pre-conditions we use the if clause and to be to + infinitive.
The structure is:
If-clause + to be to + infinitive + second clause
Example
- You must buy a helmet if you are to ride a motorbike.
- If she is to take a national flight, she must have her identity card with her.
- He should have his car insured if he is to start a road trip.
- If we are to be in Paris tomorrow, we should buy a direct flight.
- If we are to catch the inter-city bus, we should leave now.
Use
We usually use this structure with the if-clause if we want to talk about a pre-condition.
Summary
We use to be to + infinitive in the active form when we are expecting something to happen and want to talk about pre-conditions. In this case, we usually use this structure with the if-clause.
The structure is: we start with the if-clause followed by to be to + infinitive and then the second clause.
For example:
— “If you are to make a cake tonight, you shall go to the supermarket before it closes.” = We use the structure are to make with an if-clause to talk about something expected to happen, meaning the cake, and the pre-condition of having to go to the supermarket before it closes.
♦ “If you go to the supermarket before it closes, you can make a cake tonight.” = If we use the first conditional, we are not talking about something expected to happen, but about something that is possible to happen in the future.
Let’s revise this content within the {Form} section. Take a look at the {Example} section that shows its use within a context.