发生于

These events occurred in 1909.

这些事件发生1909年。

Senile dementia is a series of chronic progressive mental deterioration occurring in or pre the geratic period.

老年期痴呆是发生老年期和老年前期的一组慢精神衰退疾病。

These tumors, to date, have occurred over a wide age range in postpubertal females, are characteristically unilateral, and confined to the ovary at presentation.

到目前为止，这些肿瘤发生青期后期女的一大段年龄范围内，特征地出现，仅发生卵巢。

Therefore, the albitization of plagioclase is shown in the early stage of diagenesis and albitization of potash feldspar appears only in the late stage of diagenesis.

因此，斜长石的钠长石化可见成岩早期，而钾长石的钠长石化只发生成岩晚期。