Which have linear structure?

The molecular geometry of ${\mathrm{BeF}}_2$ is linear, with symmetric charge distribution on the central atom.

The ${\mathrm{Ag}}_{\mathrm{g}}\left[{\mathrm{CNS}}_2^{-}\right.$ geometry is linear, bond angle is 180 degrees. 

The ${\mathrm{CO}}_2$ bond angle will be 180 degrees since it has a linear molecular geometry.

${\mathrm{XeF}}_2$ has 2 bonding pairs and 3 lone pairs, so it has linear shape geometry.

Hence, the option A), B), C) and D) is correct.