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。