A—3-1eg Interchange
B—peak period
C—absolute speed limit D—acceptable gap
E—access
F—accident
G—accident cause
H—advanced public transportation services
I—air resistance
J—annual average daily traffic
K—area traffic control
L—automatic vehicle monitoring system
M—banning of turning movement
N—belt Highway
O—bike lane
( )绝对速限 ( )自动车辆监测系统

A．many more new groups of millions of stars remain unknown to us
B．stars are not in a single group
C．bigger and more powerful telescopes have been built recently
D．some stars are not single but in millions of groups