Have you ever wondered ______ there are so many natural disasters across the world in 2010?
| A．which it is that | B．what is it that |
| C．how it is that | D．why it is that |
In the past month, cruel snowstorms hit some European countries and America , _________great transportation problems in these countries.
| A．causing | B．caused | C．to cause | D．having caused |
With Halloween approaching, there exists a real concern among parents and teachers __________ trick or treating will become a seriously anti-social activity.
| A．whether | B．what | C．that | D．how |
When first __________ to the market, the computer software was not a success due to its complexity in operation.
| A．introducing | B．being introduced |
| C．introduced | D．to be introduced |
Unfortunately, the element Madam Curie devoted all her life her death .
| A．to caused | B．causing | C．to be caused | D．to causing |
Out of the crowded bus , who was dressed in a black suit and waved to a woman.
| A．a tall man in his thirties stepped | B．stepped a tall man in his thirties |
| C．did a tall man in his thirties step | D．did a tall man step in his thirties |