8.
Choose the answer which best completes the sentence in suitable and accurate English.
'They ... ... asbestos into so many schools and hospitals, if they'd known back then how dangerous it ... ... .'
... shouldn't build ... / ... was ...
... would never have built ... / ... is ...
... would never have built ... / ... was ...
... shouldn't have built ... / ... was ...
Likewise, out of context there seems little justification for the emphatic/continuous form in Answer 4 (although there's a slight sense of 'grudging', perhaps from the parent/s who bought him the original instrument and paid for lessons, as though to say 'Well, at least the early start gave him a bit of technique, and let's be glad he is still actually making some use of that instead of dropping it completely'!)