他说是疲劳导致了那个错误。
He said it was ___tiredness that caused the error.
我突然被一阵疲倦感袭来。
I was overtaken by a sudden wave of ___tiredness.
我感到如此放松,我的疲倦几乎完全消失了。
I felt so relaxed and my ___tiredness disappeared almost entirely.