Why the explosion occurred was ____ the laboratory attendant had been careless.
| A．for | B．because | C．since | D．that |
The gentleman does not ____the argument but watches the other guests.
| A．drop in | B．fill in | C．put in | D．join in |
If people keep polluting the rivers, no fish there will survive ___.
| A．at all cost | B．for a long while | C．in the long run | D．by no means |
____ the weather, the athletic meetings will be held on time.
| A．Instead of | B．In relation to | C．On behalf of | D．Regardless of |
The ground is slippery. Hold onto the rope and don’t ____.
| A．put off | B．turn up | C．let go | D．take apart |
The week-long rainfall has ___ landslides and flooding in the mountain areas.
| A．set about | B．brought about | C．come about | D．put about |