The teacher______have thought Johnson was worth it or she wouldn't have wasted time on him,l suppose.
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.
----How about the two of us chatting online? ---- ____ . It’s much cheaper than talking on the phone.