-- I heard a student killed his mother cruelly.-- So did I. It has ____ a serious problem about the education system in China.
Words failed to ________ my feelings the moment I saw my long-lost sister.
Do you know how much time and effort they devoted________ such a complicated project?
When Helen saw his tutor nod ________ to her, she calmed down and went on with her performance.
Never before________ seen a girl who can swim as fast as Ye Shiwen.
English is difficult________. Nobody can learn to use it in a few minutes.