题目内容：
Reason for cycling:By the year (16)__________ more than (17) __________ people will live in cities.
Advantage of bikes:
(i) Classic design hasn't change very much within the last (18)
(ii) It's (19)__________, reliable and (20)__________ friendly.
(iii) The lightest one is only (21)__________kilos.
Popularity:
About (22)__________percent of people in German use bikes.
(16)__________
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