______ by a greater demand of vegetables, farmers have built more green houses.
All the characteristics that distinguish birds ________ other animals can be traced to prehistoric times..
Mother made a promise ________ I passed the exam, she would buy m e a computer..
He tried his best, but he couldn’t ________ the college entrance exams last year.
Because of my poor English I’m afraid I can’t make myself ____.
I really appreciate that your help is of great _________.