单项选择题

Directions:
For each blank in the following passage, choose the best answer from the choices given below. Mark your answer on the Answer Sheet by drawing with a pencil a short bar across the corresponding letter in the brackets.
German zoologist Randolf Menzel says bees aren’t as busy as people believe they are. "Bees are not par ticularly (31) . Instead they sleep a lot and are lazy. They spend (32) 80 per cent of the night sleeping. Even during the day they often fly to the nest (33) they rest their wings," said Menzel, a zoologist at the Free University in Berlin, who has studied bees for four decades. But to (34) for their apparent laziness, they are actually very intelligent. They are (35) learners and able to recognize various smells.
Menzel said bees’ learning, like (36) of many animals, was based on a reward system. "If a bee is re warded once for something, it remembers it for a week. But if it is rewarded three times, it will remember it for its (37) lifetime," said Menzel. He was awarded a (38) by the German Zoological Society.
The memory capacity of bees means they can (39) among more than 50 different smells to find the one they want. "What is interesting is that what smells good to a bee, is also a (40) smell for humans," said Menzel.

31（）

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