**Unlimited Quizzes Await You! 🚀**
Hey there, quiz champ! 🌟 You've already tackled today's free questions.
Ready for more?
🔓 Unlock UNLIMITED Quizzes and challenge yourself every day. But that's
not all...
🔥 As a Subscriber you can join our thrilling "Daily Streak" against other
quizzers. Try to win a coveted spot on our Hall of Fame Page.
Don't miss out! Join us now and keep the fun rolling. 🎉
' ... is' (Answer 2) is slightly better than '... was' (Answer 3), because asbestos remains dangerous even nowadays, and even if it's all removed and ceases to exist, the substance still retains that theoretical property. So the present tense remains 'universally true'.
Any Answer including 'shouldn't have' will carry more of a moral force: 'they wouldn't have ...' suggests that the builders can't be faulted for not knowing what they couldn't then have known (what Donald Rumsfeld would have called 'unknown unknowns'); but 'shouldn't have' suggests that they ought not even to have started, whether or not they were sure.