If the whole operation______ beforehand a great deal of time and money would have been lost.
NASA is casting a wider net in the space shuttle investigation as to what caused the spacecraft to swing out of control and（ ） moments before it was to land.
He spent much of his lifetime, studying the disease of cattle, chickens and other（ ） animals.
Recently a number of cases have been reported of young children（ ）a violent act previously seen on television.
He was looking admiringly at the photograph published by Collins in（ ）with the Imperial Museum.
Directions: Write an essay of about 150 words on the following topic.The Covid-19 global pandemic is the most extensive to afflict humanity in a century. What do you think is the most important thing we need to do after the crisis? Please justify your idea.