Q: If I felt that my friend was not what he had been as he rambled on disconnectedly: "There were no stamps in his desk, but there might have been, eh, mon ami? , can we say that "My friend isn't acting like himself."?

A: yes

Q: If breaking down the ozone layer each flight could bring it down as much as one tenth, can we say that "Flights like that are really bad for the ozone layer."?

A: it is not possible to tell

Q: If Although a number of uncertainties remain to be addressed by continued research (NRC, 1998), a substantial body of published scientific literature recognizes a correlation between elevated PM concentrations and increased mortality rates., can we say that "There is still research being conducted."?

A: yes

Q: If Then I shan't drink it, said Tuppence firmly., can we say that "Tuppence said that she would eat it if it were frozen first. "?

A:
it is not possible to tell