Three worksheets

Worksheet 1 has values in A7:A2000
Worksheet 2 has values in B8:B18
Worksheet 3 is where I want a formula to do the following:

Worksheet3 Cell A1, for example:
Formula: If worksheet1!A10 does not equal worksheet2!b8:18, then return the
value in worksheet1!A10

Then if I drag down the formula to worksheet3!A2 , and if Worksheet1!A11
DOES equal any values in worksheet2!b8:b18, do not leave blank, but instead
fill return a value in worksheet1!A12 but only if worksheet1!A12 does not
equal any criteria in worksheet2!b8:b18, etc...

so I can pull down the formula a few hundred rows, omitting those values
that are attached to some specififed criteria as listed in worksheet 2.

Hope this makes sense... I appreciate your help... thanks...