  We collected from literature the information about large-separated pairs of
QSOs, which however once were suspected as gravitationally lensed system. We
discuss some new results on time delay determinations including optical-radio
correlations for QSO 0957+561. We considered some possible observational
effects of gravitational lensing by a cosmic string. A future international
project for observations of the gravitational lens system UM425 is briefly
discussed.
