______ a certain doubt among the people as to the practical value of the project.
| A．It has | B．They have |
C．It remains | D．There remains |
No one knows for certain how the first Americans arrived in _____ is now the United States.
| A．which | B．what | C．where | D．why |
A journal is not necessarily a reliable record of facts, for the writer’s impressions _____ colour the telling of events.
| A．must | B．shall | C．should | D． might |
She seated herself at a small table in the restaurant, waiting _____.
| A．serving | B．to serve |
| C．served | D．to be served |
Most online classes let students learn _____ their own pace.
| A．at | B．to | C．from | D．by |
_____the size of the universe, some researchers believe that there is life beyond our planet.
| A．Consider | B．To consider |
| C．Considered | D．Considering |