Had they known what was coming next, they second thoughts.
| A．may have | B．could have |
| C．must have had | D．might have had |
____ is known to everybody, the moon travels round the earth once every month.
| A．it | B．As | C．That | D．What |
I remember that _____ took part in the ball party had a wonderful time.
| A．all | B．all that | C．all which | D．all what |
. It looks ______ you are ill. You should go to see the doctor.
| A．as | B．as though | C．as well | D．even though |
Please ______ your sister to bring the ticket for the concert.
| A．remind | B．remember | C．warn | D．let |
Be careful ! The slightest spark could ______ the fireworks.
| A．set about | B．set off | C．set out | D．set up |