题干
It was ________ the exam results were given out ________ a large amount of time on computer games.
A：not until; did the boy begin to regret having wasted
B：until; that the boy didn't begin to regret having wasted
C：not until; that the boy began to regret wasting
D：until; did the boy not begin to regret wasting
答案(点此获取答案解析）
C
），则f（ 
）的值为（ ）
表示的粒子：S；④两个铁离子：2Fe3+；⑤导电、导热性最好的金属：Ag；⑥+2价的镁元素：Mg2+．其中正确的有（ ）