Bộ 10 đề ôn thi học sinh giỏi Tiếng anh lớp 9 có đầy đủ đáp án (Đề 5)

I had difficulty understanding why the machine would not start.

55/105

I had difficulty ……………… understanding why the machine would not start.

0/3000 ký tự
Giải thích

Đáp án: I had difficulty in understanding why the machine would not start.