Economics is a subject [input=type:iblank,size:4,index:0][/input]I've never understood. I want a mobile phone [input=type:iblank,size:4,index:1][/input] takes good photos.I work in that big yellow building [input=type:iblank,size:4,index:2][/input]you can see over there.Lee Harvey Oswald is the man [input=type:iblank,size:4,index:3][/input]shot John F Kennedy. A: which/that/不填 B: who/that C: which/that D: A: which/that/不填 B: who/that C: which/that