My friends and I often ___ after school.
A. went swimming       B. goes swimming       C. go swimming
解析：由句中的often可以看出本句的时态为一般现在时，所以排除A，又因为My friends and I是几个人，所以应选C

My friends and I often ___ after school.
A. went swimming       B. goes swimming       C. go swimming
解析：由句中的often可以看出本句的时态为一般现在时，所以排除A，又因为My friends and I是几个人，所以应选C