yi英语问题Mr Brown has three chilren ,one of whom is a child of

yi英语问题
Mr Brown has three chilren ,one of whom is a child of 6,_______twins f 12.
A.another B.other C.the others D.others
ur bad livng habts will destroy the earth.Only by changing______we live can we save the earth.
A.that B.what C.how D.where
-Now that you like the personal computer very much.
-well,I'd like to but I can't afford_____computer at once.
A.that expensive B.a such cheap C.that an expensive D.so cheap