--- Why don’t we take a little break? --- Didn’t we just have ?
It is strange that the small boy _________ work out such a difficult exercise, which is even hard to settle for adults.
His wife has left him, but he behaved _______ nothing had happened.
Clearly, in a system _________ every decision is made on the basis of tradition alone, it may be difficult to achieve progress.
Suddenly it _________ to me that I should report the accident to the police.
The following chapters provide step-by-step instructions for practical _______ of genetic (基因)engineering to agriculture.