This is our contribution to ________ world of the 21st century, ________ world of independence and mutual understanding.
| A．the; / | B．/; a | C．a; the | D．the; a |
（2013·北京卷) the course very difficult, she decided to move to a lower level.
| A．Find | B．Finding | C．To find | D．Found |
（2013·北京卷)When we saw the road with snow, we decided to spend the holiday at home.
| A．block | B．to block | C．blocking | D．blocked |
（2013·大纲卷）I got to the office earlier that day, the 7:30 train from Paddington.
| A．caught | B．to have caught | C．to catch | D．having caught |
______how others react to the book you have just read creates an added pleasure.
| A．Hearing | B．Hear | C．Having heard | D．To be hearing |
There are some health problems that, when ____in time, can become bigger ones later on.
| A．not treated | B．not being treated |
| C．not to be treated | D．not having been treated |