When and where to build the new factory _____not decided yet .
| A．is | B．are | C．has | D． have |
The sun rose, as it always ___, in a clear sky.
| A．is | B．does | C．likes | D．seems |
Howard Carter is one of the most famous explorers the world _____.
| A．ever know | B．ever knew |
| C．has ever known | D．will ever know |
_____ turned out that this material was neither silk nor cotton.
| A．That | B．It | C．What | D．Which |
It is believed to _____ over by sandstorms from AD 200 to AD 400.
| A．gradually cover | B．be gradually being covered |
| C．have been gradually covered | D．be gradually covered |
Many people are not fully aware of the damage that it does to their health. This is ____ we chose this picture as our logo.
| A．that | B．because |
| C．why | D．for which |