Obviously, if Aird Company knew in advance that Harder would not pay for the motorcycle, Aird would not have delivered it.

Although Aird [would / would not] knowingly sell a motorcycle to someone who is not going to pay, if some customers do not pay, there is a bad debt . Aird [must / need not] take this possibility into account in measuring its income. It does this by estimating the amount of revenue that it is reasonably certain to receive from all its sales during the accounting period.