Must Articles 2, 3, 4 and 5 of Directive 79/1072/EEC, in conjunction with Article 17(2) and (3)(a) of Directive 77/388/EEC, be interpreted as precluding a practice of a national tax administration which considers that there is no objective evidence to confirm the declared intention of the taxable person to use the goods imported in connection with its economic activity in the case where, on the date of the actual importation, the contract for the performance of which the taxable person had purchased and imported the goods was suspended, with the serious risk that the subsequent supply/transaction for which the imported goods were intended would no longer be carried out?