To her joy Della earned first the trust of her students and then of her colleagues.A. tha

问题补充：

To her joy, Della earned first the trust of her students and then of her colleagues.

A. that

B. one

C. ones

D. those

答案：

(答案→)A. that

B. one

C. ones

D. those

解析：考查代词：句意：使她高兴的是，德拉先得到学生的信任，然后得到同事的信任。这里需要代词指代trust，that是特指前面的可数名词单数或是不可数名词，而且后面有后置定语，one是泛指前面的可数名词单数，ones是泛指前面的可数名词复数，those特指前面的可数名词复数，而且后面有后置定语，所以选A。