【解析】考查动词。A. spell意味着；B. increase 增加；C. promote 促进，提升；D. threaten威胁。句意：一些科学家认为，完全人工智能的发展可能意味着人类的终结。此处表示意味着，故选A.

5. Heading out on the waters in search of whales is a routine he does, and ________ that, as he hopes, won't be lost if whale-watching goes the way of so many mass tourism attractions.

A. which B. one C. it D. that

【答案】B

【解析】考查代词。句意：在水中搜寻鲸鱼是他所做的一件日常工作，一个他希望不会丢失的日常工作，如果鲸鱼观察走的是这么多大众旅游景点的老路的话。此处代指他从事的在水中搜寻鲸鱼的工作，故选B.

6. Small and distant from cities ________ my hometown is, there is always something different to catch your eyes.

A. though B. even if C. however D. while

【答案】A

【解析】考查连词。A. though虽然，尽管；B. even if 即使；C. however 然而；D. while当...时。句意：虽然我的家乡是小而遥远的城市，但总会有不同的地方吸引你的目光。此处是though引导的让步状语从句的倒装，形容词Small and distant提前，故选A.

【名师点睛】

as/ though作"尽管"之意时，可以用于部分倒装句。一般将名词、形容词、副词、动词和分词等置于句首。如果是单数名词或形容词的最高级作表语,不再用冠词，表语中的冠词要省略。倒装的让步状语从句可用as, though 来引导，但不能用although来引导；但是未倒装的让步状语从句则可用though, although来引导，而不能用as来引导。也就是说although引导让步状语从句时不能倒装，as引导让步状语从句时必须倒装，而though引导让步状语从句时可以倒装也可以不倒装。如：

虽然很晚了，但我们还是继续工作。

正：Late as /though it was, we still went on working.

正：Though /Although it was late, we still went on working.

误：Late although it was, we still went on working.

误：As it was late, we still went on working.

7. I think ________ Aesop was suggesting is ________ when you offer a good turn to another