His loyalty to the company was in doubt.

was 是 be 动词的过去式，表示"曾经是"或"处于某种状态"。 in 是介词，表示"处于某种状态或情况中"。 doubt 是名词，意思是"怀疑、不确定"。 was in doubt 这个短语表示"曾经处于不确定的状态"，即"曾经被怀疑"或"曾经不确定"。