Write one nuclear fusion reaction.

$\underset{\text{(deuterium)}}{{}_1^{2}H}+\underset{\text{(deuterium)}}{{}_1^{2}H}\to \underset{\text{(helium isotope)}}{{}_2^{3}He}+{}_0^{1}n+3.3MeV$

$\underset{\text{(helium)}}{{}_2^{3}H}+\underset{\text{(deuterium)}}{{}_1^{2}H}\to \underset{\text{(helium)}}{{}_2^{4}He}+\underset{\text{(proton)}}{{}_0^{1}H}+18.3MeV$