Hello xman, 2- as through "She is looking as though she had been drinking heavily....." " as through" doesn't exist. The correct expression is "as though", which means 'as if' .

'She LOOKS as THOUGH she had been drinking heavily, doesn't she?' = The continuous is not used with 'look' used as a linking verb (= seem=appear) as though = as if (in a way that suggests something)

4- she is looking....., isn't she ? or & as though

The verb 'to look' here could be used to indicate both: - seem , appear: in this case "she looks..." applies. - to mean " to direct one's gaze towards" .She is probably looking at this person in a certain way conveying the state of having drunk a lot. In this case "She is looking ....." applies.