Fog(5)

'It's very nice of you,'said the man,'but I'll be off.There may be more people lost today, and I'd like to help them.You see,a fog this bad is rare.It gives me the chance to pay back the help that people give me when it's sunny.A blind person like me can't get across the road without help, execpt in a fog like this.'
(Adapted from Fog and Other Stories, Oxford Progressive English Readers@Oxford University Press 1992.)