第6部分：完形填空(第52～65题，每题1分，共15分) 下面的短文有15处空白，请根据短文内容为每处空白确定1个最佳选项。
51、回答51-65题：
Highways in the United States
The United States is well-known for its network of major highways designed to help a driver get from one place to another in the shortest possible time．__1__ these wide modern roads are generally __2__ and well maintained， with few sharp curves and __3__ straight sections， a direct route is not always the most __4__ one．Large highways often pass __5__ scenic areas and interesting small towns．Furthermore， these highways generally __6__ large urban centers which means that they become crowded with __7__ traffic during rush hours， __8__ the “fast， direct” way becomes a very slow route．However， there is almost always another route to __9__ if you are not in a hurry．Not for from the relatively new “superhighways”， there are often older， __10__ heavily traveled roads which go through the countryside．__11__ are good lane roads; others are uneven roads curving __12__ the country．These secondary routes may go up steep slopes， along hilly cliffs or down frightening hillsides to towns __13__ in deep valleys．Though these are less __14__ routes， longer and slower， they generally go to places __15__ the air is clean and the scenery is beautiful， and the driver may have a chance to get a fresh， clean view of the world．
A． Although
B．But
C．Since
D．Because
52、
A．uneven
B．bumpy
C．rough
D．smooth
53、
A．little
B．much
C．many
D．few
54、
A．terrible
B．horrible
C．tolerable
D．enjoyable
55、
A．to
B．into
C．at
D．by
56、
A．merge
B．connect
C．combine
D．mix
57、
A．busy
B．small
C．large
D．heavy
58、
A．when
B．where
C．which
D．that
59、
A．walk
B．go
C．take
D．fix
60、
A．more
B．less
C．very
D．extremely
61、
A．all of these
B．None of these
C．All roads
D．Some of these
62、
A．out of
B．out
C．through
D．from
63、
A．lying
B．lie
C．lies
D．lay
64、
A．direct
B．indirect
C．enjoyable
D．beautiful
65、
A．these
B．which
C．that
D．where
