ganesha,
when I was a beginner and wanted to break into SAP as an analyst, the interviewers threw big words like "real time gap analysis"...don't worry about these phrases. Do two things -
1. Read the theory of a functionaltiy
Say you read the theory of output determination
2. Then search the internet for with search words "Output sap sd"
Read these threads, documents.
With time and this exercise, you will gain the knowledge to answer and succeed in interviews.
Returns - comprehensive analysis
TW