Câu hỏi: Mark the letter A, B, C, or D on your answer sheet to indicate the underlined part that needscorrection in each of the following questions.
The basic elements of public-opinion research are interviewers, questionnaires, tabulating equipment, and to sample population.
A. basic elements
B. are
C. tabulating
D. and to sample
The basic elements of public-opinion research are interviewers, questionnaires, tabulating equipment, and to sample population.
A. basic elements
B. are
C. tabulating
D. and to sample
To sample => sampling vì hai động từ nối với nhau bằng liên từ and phải cùng dạng để đảm bảo sự hài hòa
Đáp án D.