2. The apparatus of claim 1 , wherein the extending module comprises: a module configured to acquire a location name in the user-inputted keywords; a module configured to determine a geographical entity referred to by the location name as a target geographical entity; a module configured to acquire adjacent geographical entities of the target geographical entity, wherein a distance between the adjacent geographical entities to the target geographical entity satisfies a criterion; and a module configured to take names of the adjacent geographical entities as an extension to the keywords.
2. The apparatus of claim 1 , wherein the extending module comprises: a module configured to acquire a location name in the user-inputted keywords; a module configured to determine a geographical entity referred to by the location name as a target geographical entity; a module configured to acquire adjacent geographical entities of the target geographical entity, wherein a distance between the adjacent geographical entities to the target geographical entity satisfies a criterion; and a module configured to take names of the adjacent geographical entities as an extension to the keywords. 4. The apparatus of claim 2 , wherein the module configured to take names of the adjacent geographical entities as an extension to the keywords comprises: a module configured to sort the adjacent geographical entities according to the corresponding distance to the target geographical entity; a module configured to select adjacent geographical entities at a front of sorting, wherein the number of the selected adjacent geographical entities is a threshold of the number of names of adjacent geographical entities; and a module configured to take names of the selected adjacent geographical entities as an extension to the keywords.