17000 bài tập tách từ đề thi thử môn Tiếng Anh có đáp án (Phần 3)

The lecture was so boring that John could hardly keep himself asleep.

548/1620

The lecture was so boring that John could hardly keep himself _____________ asleep.

of falling

to falling

from falling

in falling

Giải thích

Chọn C