31．----- Oh, my goodness! My laptop must have got stolen．
----- But where _____ a thief have entered the house with all the doors and windows still locked?
| A．should | B．could | C．dare | D．did |
They use computers to keep the traffic _________ smoothly.
| A．being run | B．run | C．to run | D．running |
The news came as no surprise to me.I _____ for some time that the factory was going to shut down.
| A．knew | B．had known |
| C．have known | D．know |
______ Tina cares about most is whether the company provides opportunities for further education.
| A．Which | B．What | C．That | D．Why |
—These grapes look really beautiful.
—They ______！See the price，$3.99 a pound.Very expensive，aren’t they！
| A．would | B．could | C．might | D．should |
There are many wonderful theme parks in America, _____ Disneyland in California is my favorite.
| A．for which | B．with which |
| C．of which | D．in which |