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。