In this article , you need to back up general statements with ________ examples.
A. specific B. permanent
C. abstract D. universal
His comprehensive surveys have provided the most__________statements of how, and on whatbasis, data are collected.
A. explicit B. ambiguous
C. original D. arbitrary
Generally,students' inner motivation with high expectations from others ________ essential to their development.
A.is B.are
C.was D.were
The university estimates that living expenses for international students ________ around $8,450 a year, which ________ a burden for some of them.
A. are;is B. are;are
C. is;are D. is;is
In our class, when the bell rang and the teacher closed his book, it was a ______ for everyone to stand up.
A. signal B. chance
C. mark D. measure
Carbon dioxide, which makes a ________ between us and the sun, prevents heat from getting out of the atmosphere easily, so the earth is becoming warmer.
A.difference B.comparison
C.connection D.barrier
