Let
f : Sp× Sq× Sr→ Sp+q+r+1,2 ≤ p ≤ q ≤ r, be a smooth embedding. In
this paper we show that the closure of one of the two components of
Sp+q+r+1−f(Sp×Sq×Sr), denoted by C1, is diffeomorphic to Sp×Sq×Dr+1 or
Sp×Dq+1×Sr or Dp+1×Sq×Sr, provided that p + q≠r or p + q = r with r even.
We also show that when p + q = r with r odd, there exist infinitely many
embeddings which do not satisfy the above property. We also define standard
embeddings of Sp× Sq× Sr into Sp+q+r+1 and, using the above result, we prove
that if C1 has the homology of Sp× Sq, then f is standard, provided that
q < r.