---Travelling by plane is _________ than travelling by train.---Yes, but it is not so ___________ as travelling by train.
When his wife died, he lived ______; his lovely pet dog made him feel less ______.
All the students know shouting at the elderly is impolite.
We can’t work out this problem. Can you tell us ______ ?
—Don't talk in the library. Always keep quiet here. —_________.
A number of foreign visitors _____ Chengdu many times because it is such a beautiful city.