MARK THE LETTER A, B, C, OR D ON YOUR ANSWER SHEET TO S...

Câu 23: Mark the letter A, B, C, or D on your answer sheet to show the underlined part that needs correction. (A) Because the expenses of (B) traditional fuels and the concern that they (C) might run out, many countries (D) have been investigating new source of power. A. Because B. traditional C. might run out D. have been investigating