Condition in Conditional (Ternary) Operator

How can I implement this using ternary operator?

if(UnitType == null)
{
    a = ElevationType
}
else
{
    a = UnitType
}

Ternary operator

a = UnitType == null ? ElevationType : UnitType;

Now I want something like this

if(UnitType == null)
{
   if(ElevationType == null)
   {
    a = StructureType
   }
   else{
    a = ElevationType
   }
}
else
{
    a = UnitType
}

Can I achieve this using ternary operator? If not, what should be done?