Question

—How often do you exercise?
—＿＿＿

1. A.
   Two
2. B.
   Twice
3. C.
   Second

Answer 1

B
词义辨析。two二，为基数词；twice两次；second第二，为序数词。根据问句“你多久锻炼一次？”，故选B。