31. To our surprise, they decided to________their differences and try to face the coming global problems together.
| A．give away | B．take up | C．put aside | D．bring down |
____________ the news, so far, has been good, there may be bad days ahead.
| A．When | B．While | C．If | D．As |
Not until the train pulled into the next station ______________ her suitcase gone.
| A．Mary had found | B．had Mary found |
| C．did Mary find | D．Mary found |
Since 1994, the glacier in Antarctica has lowered by as much as 90cm, ______________sea level to rise.
| A．having caused | B．causing | C．caused | D．being caused |
—Flight MU257 _______________ . I must be off now.
—Have a nice trip.
| A．is being announced | B．has announced |
| C．was announcing | D．had been announced |
When _______________ comes to saving energy, big changes start with small steps, like turning off the lights.
| A．that | B．this | C．it | D．one |