调查人员正在仔细检查事故现场。

The ___investigators are carefully examining the accident scene.

调查人员正在仔细检查事故现场寻找线索。

The ___investigators are carefully examining the accident scene for clues.

调查人员花了数月时间研究这种病毒的特性。

The ___investigators spent months studying the characteristics of this virus.