In a time of social reform, people’s state of mind tends to keep _______ with the rapid changes of society.
| A．terms | B．pace | C．progress | D．touch |
________ doesn’t seem to have been any difficulty solving the problem.
| A．There | B．It | C．He | D．That |
Joan had often heard ____ said that Marley had no money.
| A．one | B．it | C．once | D．her |
Carl Linnaeus made great contributions to ________ plant species.
| A．group | B．have grouped | C．grouping | D．been grouping |
He observed a stranger _______ around the store at 12 p.m. last night.
| A．to hang | B．hang | C．hanging | D．to be hanging |
Once ______ , the plan can’t be changed.
| A．begin | B．beginning | C．began | D．begun |