There is grave concern for the safety of witnesses.

证人们的安危受到严重关注。

《柯林斯英汉双解大词典》

The police have expressed grave concern about the missing child's safety.

警方对失踪孩子的安全深表关注。

《牛津词典》

Sources said he had suffered a number of very serious head injuries and there was grave concern for his life last night.

知情人士称该男生头部受了多处重伤，昨晚他的生命安危很令人担忧。

youdao

"It is clearly of grave concern to us when parliamentarians simply disappear from the face of the earth.

VOA: standard.2009.04.09

"A series of suspicious deaths in the barracks is of grave concern.

VOA: standard.2009.03.26

The resolution expresses the General Assembly's "grave concern" over the recent trial, conviction and sentencing of pro-democracy leader Aung San Suu Kyi and her return to house arrest.

VOA: standard.2009.11.20

There was alarm across the Buddhist world and the United Nations expressed grave concern.

BBC: A visit to the giant Buddhas

Mr Bett said he had consulted councils and voluntary groups and had identified causes for "grave concern".

BBC: PCC Stephen Bett fears welfare changes will cause crime

Our current spending on carriers and aircraft is a grave concern to former Navy Secretary John Lehman.

FORBES: Where are the Carriers?