One theory, ________ suggested by Harvard University, is that humans began cooking their food, thereby releasing nutrients locked in the raw food and reducing the time needed to chew it.
| A．which | B．as |
| C．that | D．what |
. She brought with her three friends, none of ______ I had ever met before.
| A．them | B．who | C．whom | D．these |
. — Why does the Lake smell terrible?
—Because large quantities of water______.
| A．has polluted | B．have been polluted |
| C．has been polluted | D．is being polluted |
Peter’s jacket looked just the same as Jack’s, but it cost ______ his.
| A．as much twice as | B．as twice much as |
| C．much as twice as | D．twice as much as |
. Everybody was touched ______words after they heard her moving story.
| A．beyond | B．within | C．of | D．in |
. Experts have warned ______ of the health risks caused by passive smoking.
| A．at a time | B．at one time | C．for some time | D．for the time |