Though I have often heard this song ______, I have never heard you ______ it.
– Tom has made great progress in spelling.– So he has and _____.
The mayor will go to Beijing by train _____ by air.
Living in a big city has many _____, such as good schools, libraries and convenient traffic.
Father _____ goes to the gym with us although he dislikes going there.
– I’m very tired.– We really should stop _____.