问答题
From the second paragraph, we can infer that
A．people belonging to the EU member states can travel freely within borders.
B．immigration to the European Union will benefit the nation's welfare.
C．the flow of people among European nations will cause troubles to transportation.
D．the mobility of cities in Europe will put urban designers in a dilemma.
A.people
B.
B．immigration
C.
C．the
D.
D．the
E.
