With sufficient scientific information a manned trip to Mars should be _____.
| A．obtainable | B．potential | C．considerable | D．feasible |
It was a small purse. I found little money in ___.
| A．itself | B．its | C．it | D．it’s |
His dog did everything he told it to do. ___ a most obedient animal.
| A．It is | B．It were | C．It are | D．It was |
___ the police three months to recover the stolen things.
| A．It needed | B．It kept | C．It spend | D．It took |
___ a very rough sea, with waves ten metres high.
| A．It were | B．This will be | C．It was | D．There’ll be |
It ___ the students in your class who came to see you then.
| A．is | B．was | C．were | D．are |