问：The survival of civilization as we know it is ____ threat .
A) within B)under C)towards D)upon
解：句意为："当今人类文明的生存正在受到威胁。"在4个选项中，只有B) under
表示"在…..情况下"或"遭到"。
Is under threat 相当于 is experiencing threat .故B)under 为解。如：
Did he do it voluntarily or under compulsion ? 他是自愿做的，还是强迫做的？
The road was under repair so we had to go round .这条道路正在修理，因此我们只得绕道而行。
The fire was soon brought under control .火势很快得到控制。
选项D）不能与threat 搭配表"遭遇"之意。Upon 可以表示"在….后立即"。如：
Upon conclusion of these studies，the patient was told that she had a severe problem.
在这些研究一有结论之后，病人就被告知有严重的博Towards 意为"向….对….."如：
The talks made little evident progress towards agreement .谈判几乎没有向达成协议的方向取得进展。
问： By the end of this month , we surely ____ a satisfactory solution to the problem .
A) have found B)will be finding C) will have found D)are finding
解：本题考核谓语动词时态的用法。句中时间状语 by the end of this month (到本月底)表示未来的某一时刻，后面说"肯定能找到一个满意的解决问题的办法"，即句子谓语动词的动作 find 要在该时刻前完成。因此需用将来完成时态。故答案为 C)
will have found .如：
when we get there they'll probably have left 我们到那里时他们可能已经走了。
He will have finished his novel by next Friday .他将在下星期五前写好他的小说。
- 考试辅导
