At the computer operation test, one is supposed to stay at his own machine, keep his eyes on his screen, ______ to anyone.
The teacher raised his voice , but still couldn’t make himslf _________.
He is a poorly learned man, but he acts as though he _____.
—I don’t suppose Jimmy could have done well in the mid-term exam last week,______? `--- ______ he almost failed in the exam.
It is strange that such a thing ______ in your school.
As is often pointed out, knowledge is a two-edged weapon which can be used ________ for good or evil.