Question

【题目】She was able to ride a bike when she was four.
A.had to
B.must
C.could

Answer 1

【答案】C
【解析】句意：四岁时她就会骑自行车。be able to=can意为“可以，能”，could的是can的过去式，而have to意为“不得不”，must“必须”，故选C。