X:
Mark the letter A, B, C, or D on your answer sheet to show the underlined part that needs correction.
Trả lời câu hỏi dưới đây:
Among the earliest telescopes were Galilean telescopes, modeled after the simple instrutments built by Galileo, the first person having used telescopes to study the stars and planets
Đáp án là A. having used => to have used. Vì sau “the first…”, ta dùng to V.