15 Đề ôn thi thpt Quốc Gia môn Tiếng Anh có lời giải chi tiết (Đề số 8)

The basic elements of public-opinion research are interviewers, questionnaires

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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.

The basic elements of public-opinion research are interviewers, questionnaires, tabulating equipment, and to sample population.

basic elements

are

tabulating

and to sample

Giải thích

Đáp án D