The retired professor, _____ in his new book in the past three years, hasn’t realized the decline in his health.
| A．involved | B．being involved | C．having involved | D．to be involved |
The chairman thought _______ necessary to invite Professor Smith to speak at the meeting .
| A．that | B．it | C．this | D．him |
------Flight 302 to London_______ until 7:30 tomorrow morning.
-----No wonder I hear so many complaints from the passengers.
| A．has been delayed | B．delay | C．delayed | D．will be delayed |
When the American constitution ______into effect in 1789,it didn’t contain any words guaranteeing the basic rights of ordinary citizens.
| A．went | B．had gone | C．has gone | D．was going |
----How have you been doing recently?
----________.Nothing really goes wrong.
| A．Good luck! | B．I’ll keep my fingers crossed | C．Can’t complain | D．So long |