He once studied in Zhejiang University, ________he went abroad for further study.
My neighbor’s daughter changed so much that I didn’t ____ her at first sight.
He had _____ me to come to the party, but he didn’t show up.
E-mail, as well as telephones, _____ an important part in daily communication.
The water will be further polluted unless some measures______.
---Excuse me, sir, is this seat taken?---_______.