Question:

You open 1 and partner responds 1NT (6-10). What is your rebid with: 

KQ2
KQ103
AQJ2
J7?

Answer:

2NT. This shows 18-19 points, just like if partner had responded 1-of-a-suit. A rebid of 3NT would say, “Partner, I don’t trust that you would know to go on after 2NT with a non-minimum).” A raise to 3NT deserves to find partner with: 

AJx
Jxx
xxx
xxxx