Sorry I’m late. I ____ have turned off the alarm clock and gone back to sleep again.
People are advised to lay particular ____ the need of a balanced diet and proper exercise.
David had prepared carefully for the chemistry exam, as he wanted to be sure of passing it at the first _____.
---I saw Mr. Smith at Xianyang Airport this morning. ---You ____. He’s still on holiday in Hawaii.
_____ much advice I gave her, she did what she wanted to do.
---- How did you know the surprising news? ---- I happened ____ the event then.