This book is __________ I can't read it.
| A．such difficult that | B．so difficulty that |
| C．such difficulty that | D．so difficult that |
______ a little earlier, you could have caught the last bus.
| A．If you would arrive | B．If you arrived | C．Should you arrive | D．Had you arrived |
You can’t complain about being left out ______you don’t make any effort to share your joys and sorrows with others.
| A．once | B．unless | C．when | D．though |
Economic growth in the world remains weak throughout 2013 and it is hoped that it will___gradually in 2014.
| A．break up | B．pick up | C．make out | D．work out |
The researchers found clear and convincing evidence _________ happiness is the key when it comes to better health and longer lives.
| A．where | B．whether | C．how | D．that |
Organized volunteering and work experience has long been ___vital companion to___ university degree courses.
| A．不填；the | B．a; the | C．a; 不填 | D．a ; a |