His deep-seated reservations about the proposed policy change were rooted in decades of practical experience.

reservations 是名词 reservation 的复数形式，reservation 来自动词 reserve（保留、预定），加上名词后缀 -ation 构成，本义是"保留意见"或"预定"。 在这里 reservations 指"保留意见、疑虑"，表示对某事持谨慎或怀疑态度。deep-seated reservations 指"根深蒂固的疑虑"，强调这种疑虑是长期形成的、难以改变的。