Not until about 2000 BC done.
A. were known of the oldest paintings
B. the oldest of known paintings were
C. the oldest known were painting
D. were the oldest known paintings
网友回答
A. were known of the oldest paintings
B. the oldest of known paintings were
C. the oldest known were painting
D. were the oldest known paintings
解析：
句意：直到公元前2000年，古人才对油画有了认识。