a.[B]

1. 中部的，中间的
   They sat in the middle row.

   他们坐在中间一排。

2. 中等的，中级的
   He was a man of middle height.

   他是中等个子。

3. （大写）中古的

n.[C]

1. 中部，中途；中央[the S]
   I was in the middle of my work when he called.

   他打电话来的时候，我正在忙。

   It is already the middle of summer.

   现在已是仲夏了。

2. 【口】（人体的）腰部

vt.

1. 把……放在中间；把……对折

vi.

1. 放在中间；对折

adj.

1. at an equal distance from the extremities of something; central.
   ▸(of a member of a group or series) placed so as to have the same number of members on each side:

   he was in his middle forties.
   ▸intermediate in rank, quality, or ability.
2. Grammar  denoting a voice of verbs in some languages, such as Greek, which expresses reciprocal or reflexive action.

n.

1. a middle point or position.
2. informal a person's waist and stomach.
3. Grammar  a middle form or voice of a verb.

v.