The number of reported crimes is increasing at an alarming rate.

　　報警案件的數量正在以驚人的速度增長。

　　The speed at which cities are growing in the less developed countries is alarming.

　　欠發達國家城市發展的.速度令人擔憂。

　　The disease is spreading with alarming rapidity.

　　這種疾病正在以令人吃驚的速度蔓延。