The only free hydrogen that survives is in pockets deep underground, part of the decay process that also forms oil and natural gas.
(The only free hydrogen; survives; ) (The only free hydrogen that survives; is; in pockets; T:deep underground) (the decay process; forms; oil and natural gas)
The only free hydrogen The only free hydrogen that survives the decay process
survives is forms
in pockets T:deep underground
oil and natural gas