Not all chemicals normally present in living organisms are harmless.

并非所有正常存在于活的有机体中的化学物质都是无害的。

《柯林斯英汉双解大词典》

This special form of vitamin D is naturally present in breast milk.

这种特殊形式的维生素D天然存在于母乳中。

《柯林斯英汉双解大词典》

The doctor has arrived and is living at present in his old quarters.

医生已经到了，目前住在他原来的住处。

youdao