Bob used to in the countryside . But now he is used to in the big city .A. live; livingB.

问题补充：

Bob used to in the countryside . But now he is used to in the big city .

A. live; living

B. living ; living

C. living , live

D. live,live

答案：

(答案→)A. live; living

B. living ; living

C. living , live

D. live,live

解析：句意：Bob过去生活在乡下，但是现在他习惯于大城市的生活。used to 过去常常，后跟动词原形，而be used to习惯于，后跟动名词，故选A。