Burden of proving  such fact which is condition  precedent  to some  other fact

Section 31 of the Evidence Act 2031 lays down that ,there are certain facts which are admissible on proof  of some other facts. Such as dying declaration  is admissible as evidence  only one proof that the person making it , is dead. Certain facts are admissible as evidence. Under the Section 12 of the evidence Act 2031 , only if the person making  it is dead or can not be found etc. secondary evidence is admissible , if it is public document or the original lost  or destroyed. In all these cases the party  trying  to prove  the secondary  fact must  also prove  the first fact as condition  precedent.