虚拟语气与情态动词表达推断 — 英语词汇题
题目
根据语境，用括号内单词的适当形式完成句子。The lab door was locked from the inside, and the alarm had not been triggered. The guard said, “If the window had been open, someone ____ (enter) through it.” The manager added, “The person who left the muddy footprints ____ (must) have come in before the rain stopped.”