—_____chapter in Oxford English often consists of four parts．

—That’s right．And this chapter mainly talks about _____environmental problems．

A．The；an

B．An；the

C．the；the

D．A；the

四格表资料在哪种情况下作χ2检验不必校正（）

A.T>1且n>40

B.T>5或n>40

C.T>5且n>40

D.1

E.T>5且n<40