Experiments of this kind __________ in both the U. S. and Europe well before the Second World War.
31.After I became the manager, few occasions could I find________I have the time to sit down and enjoy a quiet dinner with my wife.
30.I wrote emails to my sister and brother last week. To my disappointment,_______of them wrote me back.
29.Although going to school_________most of their time, students in the country always help the parents with the house-work.
28.---How did the interview go? ---Quiet well. Not so smoothly as I expected,________.
27.---Mary, you didn’t show up at the meeting last week? ---No, I________, but my son had a sudden fever and I had to stay at home to take care of him.