11.  That was the first logical thing to consider when you looked at Kiki.

12.  That was the first thing that struck me when I asked you to dance.

13.  The first living things evolved in its absence, and many organisms even today still respire without its aid.

14.  The first thing he noticed was the tang of disinfectant, mingled with the familiar smells of polish and coal ash.

15.  The first thing he saw was her blood group.

16.  The first thing I do every morning is check my email.

17.  The first thing I ever had published was an article for the Boy Scout magazine.

18.  The first thing I noticed was a small boy child, a ganymede.

19.  The first thing she did was fix him a good breakfast.