．There are five pairs______, but I’m at a loss which to buy．
A．to be chosen    B  to choose from     C . to choose     D  for choosing

Having a trip abroad is certainly good for the old couple，but
______whether they  will enjoy it.

I've worked with children before，so I know what ______ in my new job.       

The purpose of new technologies is to make life easier，______it more difficult．

Robert is said ______ abroad，but l don't know what country he studied in．

19. __________ a chance, we will visit Edinburgh a second time.

32. ---I can’t see words on the blackboard clearly .
---Why, your eyes need _____ .Perhaps you need ______ glasses .

31. Attention must be paid to ______ science and technology..

29. Heat capacity is the amount of energy it takes __________the temperature of a substance one degree centigrade.

28. This is the road ________ the mountain.