249. A_____ has taught us what atoms are made up of and how powerful the atom bomb is.
| A．seaman | B．salesman | C．naturalist | D．Scientist |
With new technology, pictures of underwater valleys can be taken color.
| A．by | B．for | C．with | D．in |
The employment rate has continued to rise in big cities thanks to the efforts of the local govenments to increase.
| A．then | B．those | C．it | D．that |
Sit down, Emma. You will only make yourself more tired, on
you feet.
| A．to keep | B．keeping | C．having kept | D．to have kept |
—Bob has gone to Califonia.
—Oh, can you tell me when he ?
| A．has left | B．left | C．is leaving | D．would leave |
The shocking news made me realizeterrible problems we would face.
| A．what | B．how | C．that | D．why |