George applied for the position three times ______ he finally got it.
| A．before | B．until | C．when | D．after |
Vitamin C helps our bodies make a special chemical, which _______ affects our brains, making us feel happy.
| A．in all | B．in turn | C．in advance | D．in short |
Sex education is a sensitive area for some parents, and thus it should remain _________.
| A．random | B．previous | C．optional | D．vital |
A _______ number of mothers with young children are stopped from undertaking paid work because they lack access to childcare.
| A．considerate | B．critical | C．fundamental | D．substantial |
All the employees complain that their boss is just _______ with promises but never with money.
| A．liberal | B．literary | C．innocent | D．impressive |
Mr. Richard was disappointed that many students who had signed up for his adventure course _______ at the last moment.
| A．left out | B．got out | C．passed out | D．dropped out |