We called for help, but it was no use as no one was around.

was 是 be 动词的过去式，表示"是"的状态。 no 是否定词，表示"没有"或"不"。 use 是名词，意思是"用处、用途"。 was no use 是一个固定短语，字面意思是"是没有用处的"，实际表示"徒劳、没用"的意思。