One of the requirements for a fire is that the material ____to its burning temperature.
A
【句意】形成火的条件之一是该材料能够被加热到燃烧的温度。
【难点】A)项requirement这个词和idea,suggestion等一样，要求从句里的谓语动词用(should)+动词原形。
When the idea of winning in sports is carried to excess, ____competition can turn into disorder and violence.
Nowhere in nature is aluminum found free, owing to its always ____ with other elements, most commonly with oxygen.
The radio is________ a strange signal. What’s wrong with it?