Tìm tâm và bán kính của các đường tròn sau:

a, x2 + y2– 2x – 2y - 2 = 0

b, 16x2 + 16y2 + 16x – 8y -11 = 0

c, x2 + y2 - 4x + 6y – 3 = 0

Mark the letter A, B, C, or D on your answer sheet to indicate the underlined part that needs correction in each of the following questions.

Buying clothes are often a very time-consuming practice because those clothes that a person likes are rarely the one that fit him or her.

A. are

B. a very time-consuming

C. because

D. are rarely the one