下列性状属于相对性状的是（ ）
A．狗的卷毛与狗的黄毛
B．骏马的奔跑与天鹅的飞行
C．金鱼的红色与鲤鱼的红色
D．兔子的长耳朵与短耳朵
同种生物同一性状的不同表现形式称为相对性状．
A、狗的卷毛与狗的黄毛，是狗毛的形状和颜色，两种性状，不是相对性状；如狗的卷毛与直毛，或狗的黄毛与黑毛，都是相对性状．故不符合题意；
B、骏马的奔跑与天鹅的飞行，是骏马和天鹅，是两个物种，不是相对性状．如骏马的快慢，或天鹅的飞行快慢都是相对性状．故不符合题意；
C、金鱼的红色与鲤鱼的红色，是金鱼和鲤鱼，是两个物种，不是相对性状．如金鱼的红色和黄色，鲤鱼的红色与黑色都是相对性状．故不符合题意；
D兔子的长耳朵与短耳朵，是兔子耳朵的长短，是同一性状的不同表现形式，是相对性状；故符合题意．
故选D．
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| From Monday to Friday most people are busy working or studying,but in the evenings and weekends they are free and 21 themselves. Some watch television or go to the movies , others 22 sports. This is decided by their own 23. There are many different ways to send our 24 time. Almost everyone has some kind of 25 : it may be something from collecting stamps to 26 model planes. Some hobbies are very 27， but others don’t cost anything at all. Some collections(收藏) are worth 28 of money，others are valuable (有价值的) only to their owners.I know a man who has a coin collection worth several 29 dollars. A short time ago he boughta rare(罕见的) fifty-cent piece which 30 him $250! He was very happy about this collection and thought the price was all right. On the other hand , my youngest brother collects match boxes，He has almost 600 of them，but I wonder 31they are worth any money. However，32 my brother they are quite valuable. 33 makes him happier than to find a new match box for his collection. That’s what a hobby means，I think. It is something we 34 to do in our free time just for the 35 of it. The value in dollars is not important，but the pleasure it gives us is. | |||
| B. work B. take care of B. interests B. free B. thing B. making B. exciting B. a few B. thousands B. cost B. if B. on B. Anything B. need B. work | C. enjoy C. think about C. jobs C. own C. job C. makes C. cheap C. a lot C. thousands of C. took C. what C. with C. Nothing C. refuse C. fun | D. play D. take part in D. things D. whole D. way D. made D. expensive D. a number D. thousand of D. spent D. why D. in D. Something D. like D. time |