The verb SHALL –
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The verb SHALL

A few children have a picnic in the park.
On the grass there is a sign:  ‘The grass shall not be stepped on.’
The children don’t see the sign and they have their picnic. The bag with food is a few steps away from them and one of the girls says:

Shall I bring some more sandwiches? I’m still hungry. You?’

‘Yes, please! Bring them all!’ says one of the boys.

When she brings the sandwiches she sees the sign and says:
‘Oh, my God, we shall not step on the grass. It is forbidden.’

 ‘We should leave the place! Come on!’ answers the boy. ‘Otherwise, we shall be fined!’

Shall we go to another park?’

Here is the lesson:

We use SHALL in many situations:

1) Future action for I and we

I shall send the information to you by tomorrow morning.

We shall go there tonight.

2) offer

Shall I bring some more bread?

Shall I help you with this bag?

3) official documents

The owner shall pay all the expenses.

The tenants shall pay the rent every month.

Typical error

For advice and suggestions, we don’t use ‘shall’, we use ‘should’.

In my opinion, we should not book another room.