It was not until all the fish died in the river the villagers realized the serious pollution.
A. where
B. that
C. what
D. which
网友回答
A. where
(答案→)B. that
C. what
D. which
解析：考察强调句型。强调句型的基本结构：it is/was 被强调成分that/who其他成分。去掉it is/was that/who句子仍然成立。本题强调的是not until all the fish died in the river.句意：直到河里的鱼都死了，村民们才意识到污染是多么的严重。