.Everyone knows that _______ is dangerous to play with fire, but _______ is difficult is to prevent children from playing with fire.
The gentleman does not ____the argument but watches the other guests.
If people keep polluting the rivers, no fish there will survive ___.
____ the weather, the athletic meetings will be held on time.
The ground is slippery. Hold onto the rope and don’t ____.
The week-long rainfall has ___ landslides and flooding in the mountain areas.