1)he insisted in sitting around the house in his swimming(trunk/trunks) 에서 왜 trunks 가 맞는지요 ?

2) but do you think he should sit in the living room in his swimwear when i have(company/a company)에서 왜 company
가 맞을까요 ?

3) two studies are (adding/adding to)the debate about the health risks.에서 왜 adding to가 맞는지요 ?

4)a winning coach can not afford to let little things go unnoticed because that often ( cause/causes) the difference
between success and failure.에서 왜 causes 가 답일까요 ???????

너무 궁금해요.. 명쾌한 답변 부탁드립니다...