With a coordinator or subordinator:It is Mary’s sister ______spe

With a coordinator or subordinator:
It is Mary’s sister ______speaks Chinese best in her class.
【正确答案】：who/ that
【题目解析】：此为强调主语的强调句，去掉强调结构It is (was) … that(who)…后，剩下的词仍能组成一个完整的句子。