| 摘要 |
A letter card having a covering with a tear line on the inside, and a shaped inflatable device received inside the covering, the shaped inflatable device holding an acidic chemical means and a separating layer and a basic chemical means separated from the acidic chemical means by the separating layer, the acidic chemical means and the basic chemical means being mixed together to produce a chemical reaction and to release a gas when breaking the separating layer by force, thereby causing the shaped inflatable device to swell and to come out of the covering.
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