Of the two T-shirts, I’d choose _________ one to save some money for a book.

Is the man standing outside the teacher’s office Mr. Zhou? –No, it ______ be him. He has gone to Hong Kong for an academic conference.

Some scientists believe that there will be more robots inyears.

Some little boys have difficulty ______their hearts into the lesson for a long time.

Will you get there by _____ train? – No, I’ll take _taxi.