His health has picked up noticeably since switching to a new doctor.

pick up 是一个短语动词，由动词 pick（拾起）和副词 up（向上）组成。 pick up 在这里的意思是"好转、改善"，特别指健康或经济状况的恢复或提升。这个短语动词常用于描述情况逐渐变好的过程。