Change the voice of the following: 

a) It is time to do the work.

b) Green mangoes taste sour.

c) Circumstances obliged me to go.

d) They proposed to hold a meeting.

e) Do not hate the poor.

(a) It is time to do the work.

Ans : It is time for the work to be done.

(b) Green mangoes taste sour.

Ans : Green mangoes are sour when they are tasted./Green mangoes are tasted sour.

(c) Circumstances obliged me to go.

Ans : I was obliged to go (under circumstances).

(d) They proposed to hold a meeting.

Ans : A meeting was proposed to hold by them.

(e) Do not hate the poor.

Ans : Let the poor not be hated.