Without the computer ______  ______ (出故障), I would have finished my task on time.
Exhausted, he ______  ______ (溜进) bed and fell fast asleep after the long journey.
A knowledge of first aid ______  _____  _____________(起作用) to saving our lives.
He ______ the class ______（把..分成）two groups and had a debate.
____  _____________(巧合)，we all have a poor sense of direction and are lost here.