4.241 stating an intention
You can use 'be going to' instead of 'will' to state an intention.
4.242
You use 'intend to' to state a fairly strong intention.
4.243
You use 'be determined to' or 'be resolved to' to indicate a very strong intention to do something. 'Be resolved to' is rather formal.
4.244
You can use 'have to' or 'have got to' instead of 'must' to indicate that it is important that you do something.