After the happy summer vacation, scientists began to study again.
Professor Smith's lecture on poetry left a deep impression on the audience.
Dr Smith's lecture on poetry left a deep impression on the audience.
Young people prefer camping to watching TV at home.
Young people prefer camping to watching TV at home.
Tom glanced at the envelope and immediately recognized his father's signature.
Tom glanced at the envelope and recognized his father's signature.
Telephone has become the most convenient way for people to communicate with each other.
Telephone has become the most convenient way for people to communicate.
The snowstorm caused all contact with ships at sea.
The storm caused the interruption of communication with ships at sea.
If you are in trouble, don't hesitate to ask me for help.
If you have any difficulties, please come to me without hesitation.
It is impolite for you to stare at the disabled in the street.
It is impolite for you to stare at the disabled in the street.