но у них сменилось так много учител

но у них сменилось так много учителей,что они разучились работать

Results (English) 1:

but they had so many teachers that they have forgotten how to work

Results (English) 2:

but they have changed so many teachers that they have forgotten how to work

Results (English) 3:

But they have changed so many teachers,that they Vladimir Ustinov to work