叛军对村庄发动了无情的袭击。

The rebels launched a ___merciless attack on the village.

她对他工作的批评毫不留情。

She was merciless in her ___merciless criticism of his work.

她对同事的无情行为最终导致她被解雇。

Her ___merciless behaviour towards her colleagues eventually led to her dismissal.