Task: Question Answering
Input (English): As is so often the case , we first directed to the " pop - rivets " , and then got the " I haven't seen those in ages " treatment from the assistant . We bought some flat headed nails and washers to fit them , which is a substitute that I've used in the past . We were also picking up some computer parts , but when we arrived at the shop , first there was a problem with the payment which was quickly resolved ( we were just collecting not paying ) , then the parts were not in the shop ! Whilst waiting , we went across the road to a Thai restaurant for their " set lunch " . 
Question: What's a possible reason they bought some flat headed nails and washers ?
Output (English): Because they needed to build or repair something .