________ bikes have been stolen from the department store．

A number of

The number of

A great deal of

A great many of

It was three years ________ he went back to his hometown．

that

before

when

if

I should thank you ________ you thank me．

as though

even though

rather than

in case

She solved the problem ________ one might be expected．

as

for

since

because

He was so young ________．

and he couldn’t understand

but he couldn’t understand it

so he couldn’t understand it

that he couldn’t understand it

He got up very early ________ he could catch the train．

if

though

in order that

only if

They have been doing their homework ________ they came from the school．

as

since

while

because

________ environmental damage is done, it takes many years for the ecosystem(生态系统)to recover．

Even if

If only

While

Once

Jenny was very sad over the loss of the photos she had shot at Canada, ________ this was a memory she especially treasured．

when

where

as

if

A dozen ideas were considered ________ the chief architect decided on the design of the building．

because

before

whether

unless