______ bears’ number has increased, their conflicts with local people have increased too.
| A．If | B．With | C．As | D．While |
32. ––When will you be back, Peter?
––________a couple of days.
| A．On | B．In | C．For | D．By |
31. All books ______ to the library more than three days late will be subject to a fine.
| A．return | B．returning | C．to return | D．Returned |
30. When he was only thirty years old, he had already experienced______most people only experience when they are much older.
| A．what | B．which | C．who | D．When |
29. ______ in the sports world, a sportsman needs to train constantly to keep himself in best condition.
| A．Survive | B．Surviving | C．To survive | D．Survived |
28. Listen, Mike. She_________have done it. She’s been with me at the shop all day.
| A．couldn’t | B．shouldn’t | C．needn’t | D．wouldn’t |