单选题9. Bob ______ hard, otherwise he ______ this exam.

单选题 Since his wife died

单选题 In this age of equality

单选题14. No permission has ______ for anybody to take photos here.

单选题 I don't think he will finish the project on time

单选题55. If only you ______ him what I said! Everything would have been all right.

单选题3. ______ the English examination I would have gone to the concert last night.

单选题 In 2012

单选题 While ______ your imagination

单选题 To our great surprise, Mr

单选题 Everything ______ into consideration

单选题30. I am ______ grateful for the kindness you have shown my son.

单选题 Three days later

单选题11. Under no circumstances ______ the party.

单选题22. On his way home he was killed in a car ______.

单选题12. Notice a person's reaction ______ stress in these situations, and you will soon find a solution ______ this problem.

单选题 You can do it if you want to

单选题. Why don't birds get lost on their long flights from one place to another? Scientists have puzzled over this question for a long time. Now they're starting to fill in the blanks. Not long ago, experiments showed that birds use the sun to guide them during daylight hours. How do birds fly at night? Tests with artificial stars have proved that certain night-flying birds are able to follow the stars in their long-distance flights. A dove had spent its lifetime in a cage and had never flown under a natural sky. But it had an inborn ability to use the stars for guidance. The bird's cage was placed under an artificial star-filled sky. The bird tried to fly in the same direction as that taken by his outdoor cousins. Any change in the position of the artificial stars caused a change in the direction of his flight. But the stars are apparently their main means of navigation. When the stars are hidden by clouds, they apparently find their way by such landmarks as river courses, mountain ranges, coast lines. But when it's too dark to see these things, the doves circle helplessly, unable to find their way.1. The reasons why birds don't get lost on their long flights ______.

单选题20. It was not until he arrived in class ______ realized he bad forgotten his book.

单选题27. Nobody but Smith and John ______ in the lab yesterday.