Mrs Smith worked day and night, he found it difficult to make enough money to support such a large family.
A. Since
B. If
C. Once
D. Although
网友回答
A. Since
B. If
C. Once
(答案→)D. Although
解析：考查连词：A. Since自从B. If如果C. Once一旦D. Although虽然，句意：虽然斯密斯太太日日夜夜工作，但她发现很难挣足够的钱养活一家人。选D。