Oliver still bought some goldfish he found it difficult to raise them.A. becauseB. sinceC.

问题补充：

Oliver still bought some goldfish he found it difficult to raise them.

A. because

B. since

C. though

D. until

答案：

A. because

B. since

(答案→)C. though

D. until

解析：词义辨析。Because因为；since自从，因为；though尽管；until直到。句意：Oliver仍然买了一些金鱼尽管他发现饲养它们很难。所以选C。