英语句子分析,

题目

英语句子分析,
例如这句,句子的主干（就是主谓宾的那种）里存在but吗?存在时间（Early in the nineteenth century）吗?
Early in the nineteenth century,encounters with Aboriginal rock art tended to be infrequentand open to speculative interpretation,but since the late nineteenth century,awareness of the extent and variety of Australian rock art has been growing.

答案