He is trying to improperly influence a witness.

他正试图不适当地影响一名证人。

《柯林斯英汉双解大词典》

Bad air quality can contribute to many health problems such as asthma, and improperly discarded garbage can spread bacteria that are dangerous to health.

糟糕的空气质量会导致许多健康问题，比如哮喘，而丢弃不当的垃圾会传播细菌，危害健康。

youdao

He was improperly dressed for the occasion.

他的衣着不大适合这个场合。

《牛津词典》

The investors want the bank to buy back any improperly processed loans included in those securities.

VOA: special.2010.10.22

Dr.Nissen points out that many over the counter drugs - aspirin,ibuprofen, acetaminophen or paracetamol - can be toxic if used improperly.

VOA: standard.2010.03.02

Companies can now suffer substantial losses when their products are improperly used even when users are amply warned.

FORBES: Supremely Destructive Stupidity

Those checks did not turn up anything to indicate the burial was done improperly.

CNN: Sheriff: Tamerlan Tsarnaev's burial was handled properly

Improperly filling out a ballot is "the number one way people disenfranchise themselves, " McDonald said.

CNN: In voting, the early bird skips the line