警方担心那对夫妇可能已经溺水身亡。

Police ___fear that the couple may have drowned.

据信有多达两百名乘客在坠机事故中丧生。

It is ___feared that as many as two hundred passengers died in the crash.

我们担心子孙后代将面临严峻的环境挑战。

We ___fear that future generations will face serious environmental challenges.