The diamond mine ________ accidentally by a little boy when he was playing hide-and-seek．

A．discovered

B．was discovered

C．has been discovered

D．would discover

Before I began this job, I ________ a baby sitter for two years．

A．have been

B．was

C．would be

D．had been

After the accident, we are ________ concerned with the safety of school buses than we used to be．

A．little

B．less

C．much

D．more

You ________ bring your identification when you open a bank account．

A．may

B．can

C．must

D．will

They don't come to the book club any more, for ________ reasons or other．

A．some

B．all

C．either

D．both

A huge amount of money has been spent ________ the new bridge．

A．in

B．on

C．with

D．for

Don't handle the vase as if it ________ made of steel．

A．is

B．were

C．has been

D．had been

Do you think this shirt is too tight ________ the shoulders?

A．at

B．on

C．to

D．across

We ________ the difficulty together, but why didn't you tell me?

A．should face

B．might face

C．could have faced

D．must have faced

Birds' singsing is sometimes a warning to other bird ________ away．

A．to stay

B．staying

C．atayed

D．stay