________ useful work they have done!

A．What

B．How

C．What an

D．How an

When class began, we stopped ________ and listened to the teacher carefully．

A．talking

B．to talk

C．talks

D．talk

I ________ a chance to be a monitor, but I refused．

A．offered

B．had offered

C．was offered

D．was offering

I haven't heard from my best friend ________．

A．last year

B．a year ago

C．since last year

D．for last year

It's really kind ________．

A．for you to say so

B．for you saying so

C．of you to say so

D．for you saying

Last weekend many people went to the concert, ________ young people．

A．hardly

B．probably

C．mostly

D．really

The light in the room is not ________ for me to read．

A．brightly enough

B．enough brightly

C．enough bright

D．bright enough

Nothing can stop the sandstorm ________ more and more trees are planted．

A．unless

B．if

C．when

D．while

If there is no traffic, I will run ________ the road．

A．over

B．across

C．through

D．from

The man opened the ________ door ________ and came in without any sound．

A．secret; quiet

B．secretly; quietly

C．secret; quietly

D．secretly; quiet