--instructions--

Listen to the audio and complete the sentence below.

--fillInTheBlank--

--sentence--

It BLANK BLANK BLANK last night because that's when we started noticing unusual activity on the servers.

--blanks--

must

--feedback--

This modal verb expresses strong certainty about something in the past.

have

--feedback--

This word is needed in perfect verb forms.

happened

--feedback--

This is the past participle of happen.

--explanation--

Must have happened is used to make a logical guess about something in the past.

Must expresses strong certainty. Have + Past Participle (like happened) refers to something in the past. For example:

• He must have forgotten to update the system. - It's likely that he didn't remember to do the update.

• They must have made some changes to the app. - It's likely that the app has been updated or improved.

Jake is using evidence (unusual activity on the servers) to conclude that the breach must have happened last night. This structure is useful for making logical assumptions.

--scene--

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  "setup": {
    "background": "company2-center.png",
    "characters": [
      {
        "character": "Jake",
        "position": {
          "x": 50,
          "y": 0,
          "z": 1.4
        },
        "opacity": 0
      }
    ],
    "audio": {
      "filename": "B1_14-3.mp3",
      "startTime": 1,
      "startTimestamp": 10.28,
      "finishTimestamp": 15.02
    }
  },
  "commands": [
    {
      "character": "Jake",
      "opacity": 1,
      "startTime": 0
    },
    {
      "character": "Jake",
      "startTime": 1,
      "finishTime": 5.74,
      "dialogue": {
        "text": "It must have happened last night because that's when we started noticing unusual activity on the servers.",
        "align": "center"
      }
    },
    {
      "character": "Jake",
      "opacity": 0,
      "startTime": 6.24
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}