1 to do

2 to make

3 to produce

4 to write

5 to compose

6 to act as

7 to engage in

8 to hold (a party)

9 to be

10 to become

11 to function (in some capacity)

12 to serve as

13 to be used for

14 to form (a bond or relationship)

15 to pretend

16 to feign

17 to act a part

18 to put on appearance

1 partner

2 companion

3 comrade

1 partner

2 companion

3 comrade

4 associate

5 to accompany

1 companion

2 mate

3 partner

1 bridesmaid

2 maid of honor

3 matron of honor

1 don't do it, or don't rest (idiom); either give up, or go through to the end

2 Since we started, we must carry it through whatever happens.

3 in for a penny, in for a pound

1 being close to the sovereign can be as perilous as lying with a tiger (idiom)

1 lit. as a monk for today, toll today's bell (idiom)

2 fig. to do one's job mechanically

3 to hold a position passively

1 to persuade using all possible arguments (idiom); to act good cop and bad cop in turn

1 to put on an act (idiom); to pose

2 to show theatrical affectation

3 to indulge in histrionics