Answers 15A - how do you form the:
Past Simple: verb+ed or an irregular verb.
Questions: did +verb stem.
Negations: did+not/n’t + verb stem
Present Perfect: have/has + past participle or have/has + irregular past part.
Questions: you change the order of the subject and the auxiliary.
Negations: you put 'not/n't' between the auxiliary and the main verb.
Present Perfect Continuous: have/has + been + verb stem+ -ing.
Questions: you change the order of the subject and the auxiliary.
Negations: you put 'not/n't' between the first and the second auxiliary.