“Sorry” is a word that people in Britain often say in their daily life.

    One day while I was w____on the street, a young man ran by hurriedly, brushing(轻擦) against my handbag. He continued his way, but turned b____and said “sorry” to me. Even in a rush, he didn't f____to say “sorry”. One day, after I bought some bananas, the shopkeeper was passing me the change, but I wasn't ready for it and a coin dropped onto the ground. “Sorry, Madam,” he said w____bending to pick it up. I was s____why he said “sorry” to me. Another time, I stepped on a man's f____at the entrance to a cinema. At the same time, we b____said “sorry”.

    Slowly, I got to know that when something unpleasant happens in daily life, the British don't c____much about who is wrong. If someone is in trouble, a “sorry” is always n____. Perhaps that is w____I seldom see people quarrel on the buses or streets in Britain.

下列词语中，没有错别字的一组是（    ）

①钙原子的核电荷数为____，氟元素的相对原子质量为____。

②X=____；A、B、C、D中属于同种元素的粒子是____（填序号）。

③A粒子的化学性质与B、C、D中哪一种粒子的化学性质相似____（填序号）。

④17号元素在元素周期表中位于第____。

⑤9号与20号元素形成化合物的化学式是____。