He will give us a report on how to study English well, but when and where ________.
A. is still unknown. B. hasn’t decided
C. is known D. haven’t been decided
We should work together to build a society for kids, ________free from war and violence.
A.one B.this C.it D.that
He slipped(溜进) into the classroom without ___________.
A. noticed B. noticing
C. being noticed D. was noticed
This special strain of rice makes _________ possible to produce one third more of the crop in the same fields.
A. it B. them C. which D. that
---Is that the small town you often talk about?
---Right, just the one ______________ you know I used to work for three years.
A .that B.which
C.where D.what
Although the first part of the book is easy， the rest ______.
A. has proved difficult B. are difficult
C. is supposed difficult D. have been found difficult
