Based on the clue 'a simulated 3 d environment that a user can experi...', what is the answer?

Based on the clue 'a simple structure for transport on water', what is the answer? Based on the clue 'a simple way to make a room seem bigger is to hang...', what is the answer? What is associated with: a simple white cross marks the grave of this attorney general buried near his brother in 1968? Based on the clue 'a simpler way of saying more lobster colored', what is the answer? Based on the clue 'a simultaneous discharge of rifles', what is the answer? What is referred to by 'a sin for example'? Based on the clue 'a sincere cavalier he fooled around with guinevere', what is the answer? Based on the clue 'a singable poem perhaps of the last minstrel 3', what is the answer?