Lindelof property and absolute embeddings

It is proved that a Tychonoff space is Lindelof if and only if whenever a T ychonoff space Y contains two disjoint closed copies X-1 and X-2 of X, then these copies can be separated in Y by open sets. We also show that a Tycho noff space X is weakly C-embedded (relatively normal) in every larger Tycho noff space if and only if X is either almost compact or Lindelof (normal al most compact or Lindelof).