Answer:
Because of my sore throat, my singing is bad today. But it was worse yesterday.
Step-by-step explanation:
The comparative degree of an adjective is used in the above sentence. When two things or two people are compared with each other, the comparative degree of an adjective is used. In the above sentence, the soreness of the thought has been compared between 'today' and 'yesterday'. Therefore, the comparative degree of 'bad' which is 'worse' is used.