题干
—Look! So many colorful bicycles in two lines over there.
—They're for public. This of green smart traffic is everywhere in Xiangyang city.
A：number
B：pair
C：kind
D：piece
答案(点此获取答案解析）
C
人向右匀速推动水平桌面上的长木板，木板露出桌面后，在木板翻离桌面以前，则