_________ caused the accident is still a mystery.
| A．How | B．What | C．That | D．Where |
I think they’ve got to the very point _______ a change is needed, or they will fail.
| A．when | B．which | C．where | D．that |
He had no sooner arrived there ________ pestering his doctor.
| A．and then he began | B．when he began | C．to begin | D．than he began |
. While s
hopping, people sometimes can't help _______ into buying something they don't really need.
| A．to persuade | B．persuading | C．being persuaded | D．be persuaded |
With no one to ______ in such a frightening situation, she felt very helpless.
| A．turn on | B．turn off | C．turn around | D．turn to |
_______ from other continents for millions of years, Australia has many plants and animals not found in any other country in the world.
| A．Being separated | B．Having separated |
| C．Having been separated | D．To be separated |