calling help signal

例句：

1. 1. The police are calling for witnessesto come forward.
   警方正在呼吁目击者前来作证。
2. 2. The doctor called meto say he would be late.
   医生打电话给我，说他会迟到。
3. 3. Thecaller left a messageasking for directions.
   来电者留言询问如何到达目的地。