Rule reminder
'Quasi che' (as though, as if) is a formal and literary alternative to 'come se'. It is followed by the congiuntivo imperfetto (for present/habitual unreal comparisons) or congiuntivo trapassato (for past unreal comparisons). It is rarely used in everyday speech — it belongs to elevated or written registers. Example: Lo guardò quasi che fosse un fantasma. (He looked at him as though he were a ghost.)
Si fermò d'improvviso, quasi che _____ qualcosa di strano.