Vitamin D helps our bodies make a special chemical, and this special chemical, ________, affects our brains, making us feel happy.
| A．in turn | B．in particular | C．in advance | D．in short |
The field research will take Joan and Paul about five months; it will be a long time _____ we meet them again.
| A．after | B．before |
| C．since | D．when |
All the travelers _____that they should bring their ID cards with them.
| A．have reminded | B．are reminded |
| C．were reminding | D．had been reminded |
There is a big dog _______to a fence outside the house.
| A．tying | B．tied |
| C．to tie | D．ties |
The fog was so heavy this morning that drivers could hardly ________ the things just ten meters away from them.
| A．turn out | B．look out |
| C．let out | D．make out |
This is the most serious and worst situation ___ I have ever experienced as a fan of the NBA.
A. which B. that
C. whenD. where