________ several times, Bill made up his mind not to watch late night movies any more.
| A．To be blamed | B．Having blamed | C．To blame | D．Having been blamed |
A dark blue design will not on a blackboard.
| A．clear up | B．go up | C．show up | D．pick up |
The store had to a number of clerks because sales were down.
| A．lay out | B．lay off | C．lay aside | D．lay down |
It is much easier to talk about social change than to .
| A．bring it on | B．bring it about | C．bring it up | D．bring it out |
This is a story completely by him, so don’t rust him.
| A．discovered | B．invented | C．found | D．known |
Historical experience can as a most important source of information.
| A．serve | B．use | C．regard | D．prove |