vi.[(+from)]

1. 戒；避免；避开
   The doctor asked the patient to abstain from smoking.

   医生叫这位病人戒烟。

2. 弃权
   Some voters abstained in the election.

   一些选民在选举中弃了权。

v.

1. (often abstain from) restrain oneself from doing something.
2. formally decline to vote.