see

saw

have seen

will see

She ________ to her feet and ran out of the room just now．

jumped

jumps

was jumping

will jump

Ask John ________ here at 7 pm tomorrow．

come

coming

came

to come

The air in Beijing is getting much ________ now than a few years ago．

clean

cleaner

cleanest

the cleanest

He has two pets．One is a dog, ________ is a cat．

the other

other

others

another

I phoned you at six yesterday evening, ________ nobody answered．

because

or

but

so

There ________ little water in the river．

be

am

is

are

It’s very nice to visit New York ________ autumn．

in

on

at

of

These photos ________ by my sister on Mount Tai last summer．

take

took

are taken

were taken

Mike and I ________ net-friends．We talk on-line every week．

am

was

are

is