$R^{2}or{R}^3\{(x,y)in{R}^2$:$x^2+y^{2}1\}$

$(b)\{(x,y,z)in{R}^3$:$-1x,y,z1\}$

$(c)\{(x,x^2,x^4)in{R}^3$:xin$[0,1]\}$

$(d)\{(x,y,z)in{R}^3$:$z=x+y,$xinR,yin$[0,1]\}$