The credit card, an American innovation, first gained national【48】in 1938【49】oil companies selling gasoline to【50】set up a national pool to honor each other's cards. Rapid growth,【51】, was not possible【52】the mid-1950's,when the development of electronic computers【53】fast, accurate billing and accounting. Department stores, airlines, banks, and other enterprises then entered the【54】and now offer credit to【55】140 million card owners.
(46)
A.mean
B.means
C.methods
D.ways
(56)
A.bachelor
B.young man
C.single
D.spinster
(61)
A.As
B.When
C.While
D.Whether