I was writing a report last night; ________ I would not have stayed up late.
B
我昨天晚上写一个报告，否则我就不会熬夜了。考查副词词义选择题。A然而，不过B否则，要不然C因此，所以D再者，而且
Thisisanimportantproblem_______toofewsocialscientistshaveresearched.
Johnsonwas________unknownbeforerunningforthepresidency.
Iaskedhimto________meafewminutessothatwecouldgooveralltheproblems.
Theoldcouplehavebeenmarriedfor40yearsandneveronce_______witheachother.