题目内容：

1 l the photographs in this book,________stated otherwise ,date from the 1950s
A unless B until Conce D if
为什么选A,求翻译加解释,
2.He tried his best to solve the problem ,______difficult it was
A however
B no matter
C whatever
D although
为什么选A,
3______________the police thought he was the most likely one,since they had no exact proof about it,theycould not arrest him
A AIthough
B AS long as
C if only
C AS soon as
为什么选A,求翻译加解释