Reply to 1-4 using the formal modal + have + past participle, plus an explanation. Choose from the following: should, shouldn't, must, might, mightn't, may, could, couldn't, can't. Example: There's no reply - maybe he's gone out. He must have done. He said he had to go out at eight. 1. I can't believe he really did something as stupid as that 2. Perhaps she's finished getting ready by now. 3. You don't think they've left already, do you? 4. Surely it didn't happen that long ago?