adverbial clause of purpose.

‘because’ and ‘because of’

e.g. 4. The plane did not take off at the scheduled time because of bad weather.

In e.g. 1, ‘because’ is a conjuction used along with a subject and verb. It forms a subordinate clause that is, an adverbial clause of
reason.

But in e.g. 4, ‘because of bad weather’ is only a phrase.

B. ‘So as to-infinitive’ and ‘so that’ are used to show the expected result of the action mentioned earlier in the sentence.

I always make notes so as to refer to it later.

The italicised part is a phrase.

The same sentence can also be written as - I always make notes so that I can refer to it later.

The italicised part is a subordinate clause, that is an adverbial clause of purpose.

‘In order’, to - /(infinitive)’ and ‘ in order that’ are used to state the purpose of the first action mentioned.