第 31 至 35 題為題組
        Do you have trouble getting started in the morning? Do you have problems learning early in the day?If you do, you are not alone. __31__ They learn better at night than they do in the morning.To investigate when cockroaches learn best, researchers at Vanderbilt University tested the insectsfor which odor (peppermint or vanilla) they preferred. Most cockroaches preferred the smell of vanilla tothat of peppermint at all times. __32__ Therefore, the scientists trained the cockroaches to prefer thepeppermint smell by rewarding the insects with a taste of sugar water when they approached a peppermintsmell. __33__       When the cockroaches were trained at night, they remembered the new associations (peppermint =sugar water； vanilla = salt water) for up to 48 hours. However, if the cockroaches were trained in themorning, they quickly forgot which smell went with which water. __34__So, cockroaches learn better at night than they do in the morning. __35__ Because of this, it islikely that information they gather at night will be more useful to them. These experiments provide someclues about the interactions between body rhythms, learning and memory. 
(A) When these insects moved toward a vanilla smell, on the other hand, they were punished with ataste of salt.
(B) This result thus shows that the time when they were trained decided the effect of their learning.
(C) They are often more active and tend to search for food during the night.
(D) They were also found to like sugar water, but not salt water.
(E) Cockroaches have the same problem!
【題組】31.