vi.

1. 有用；有益，有帮助[（+against）]
   The medicine did not avail against the disease.

   该药对此病无效。

vt.

1. 有用于；有益于；有助于
   He availed himself of the opportunity to speak to her.

   他利用这机会和她说话。

n.

1. 效用；利益；帮助[U]
   Speeches and protests were of no avail.

   演讲和抗议全都徒劳。

2. 【古】利润；（尤指卖掉财产后的）所得[P]

v.

1. (avail oneself of) use or take advantage of.
2. help or benefit.

n.