指想说什么又没有说出来to have something on the tip of one's tongue that one does not let out

• 长春市第四看守所民警发现在押人员王某神情闪烁，欲言又止。

  Civil police in Changchun No.4 Detention Centre discovered that detainee Wang X had something on the tip of his tongue that he did not let out.

• 面对一家人的责问，赵维富欲言又止。

  Confronted with the reproaches of the whole family, Zhao Weifu wanted to say something but then thought better of it.