We must do everything we can _________ our earth clearer and safer.
A．made B．to making C．make D．to make
We all know that paper burns in _________ .
A．CO2 B．N2 C． O2 D．CO
This is one of the best films _________ this year.
A．have been shown
B．that have shown
C．that have been shown
D．which has been shown
________ our journey by camel was!
A．What an exciting experience
B．What exciting experience
C．How excited experience
D．What an excited experience
--- I don’t mind telling you what I know.
--- You _______. I’m not asking you for it.
A．may not B．can’t C．don’t have to D．mustn’t
About _______ of the books in our school library are written in Chinese.
A．four-fifth B．four-fifths
C．fourth-fifths D．fourths-fifth
