Tom’s uncle knows computers well, and he __________ a computer engineer .

—Why are your eyes so red？You________have slept well last night.—Yeah，I stayed up late writing a report.                          (

---Did they have a good time at the party?---Judging by their smiles, they _________ have enjoyed themselves.

—Why don’t you wear your jogging shorts, mum?—Well, my legs are too skinny, if you ______ know. 

 My English-Chinese dictionary isn’t in my schoolbag. Where _________ I have put it?