How to sum up data with dynamic selection using formula in Excel?

Hello all,

How to sum up the data with dynamic selection using formula in Excel?

For example:

In row 1, I wanted sum up columns A, B, C, D, E, F, G, H values but I want to skip column D.

In row 2, I wanted sum up columns A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q values but I want to skip column J
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???..

As there are 1,000 records, could anyone advice how to do that in effective way? Many thanks for your help!