完形填空。 The first time I remember noticing

     The first time I remember noticing the crossing guard was when he waved to me as I drove
my son to school.He__1__me with a puzzle-all because he waved to me like someone does
__2__ seeing a close friend.A big,__3__smile accompanied his wave.For the next few days
I tried to__4__his face to see if I knew him.I didn't.Perhaps he had__5__me for someone else.
By the time I contented myself with the__6__that he and I were strangers,we were greeting
each other warmly every morning like old friends.
     Then one day the__7__was solved.As I__8__the school he was standing in the middle of
the road__9__his stop sign.I was in line behind four cars.__10__the kids had reached the safety
of the sidewalk,he lowered his sign and let the cars__11__.To the first he waved and__12__in
just the same way he had done to me over the last few days.The kids already had the window
down and were happily waving their reply.The second car got the same__13__from the crossing
guard,and the driver,a stiff looking(表情刻板的)businessman,gave a brief,almost__14__wave
back.Each following car of kids on their way to school__15__more heartily.
     Every morning I continued to watch the man with__16__.So far I haven't seen anyone__17__
to wave back.I find it interesting that one person can make such a(n)__18__to so many people's
lives by doing one simple thing like waving and smiling warmly.His__19__armed the start of my
day.With a friendly wave and smiling face he had changed the__20__of the whole
neighbourhood.