Classify the solution set of each equation below as one of the following types of surfaces: A. parabolic cylinder,   B. ellipsoid,   C. elliptic paraboloid,
D. hyperbolic paraboloid,   E. cone,   and   F. hyperboloid.

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	1.	$y^2=x^2+\frac{1}{9}z^2$
	2.	$4x^2-y+2z^2=0$
	3.	$x^2+2y-2z^2=0$
	4.	$y^2=x^2+4z^2+4$

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