21．If there’s a lot of work________，I’m happy to just keep on until it is finished.
A．to do B．to be doing C．done D．doing
22．There is no that the Great Wall of China is one of the biggest manmade
projects on the earth.
A．time B．doubt C．matter D．mind
23. Don’t be too about things you are not supposed to know.
A．strange B．amusing C．curious D．conscious
