冠周炎的病因是
A.因智齿萌出最晚B.冠周龈瓣易堆积食物及细菌C.颌骨长度不足D.下颌智齿发育异常E.邻牙牙周炎
参考答案:B
一只白色母狗与一只白色公狗交配,一窝生了4只小狗,其中3只白色、1只黑色,请据此回答问题。
(1)狗的毛色,如白色和黑色在遗传学上称作
(2)请你推断狗毛的白色和黑色中,显性性状是
(3)如果显性性状由基因A控制,隐性性状由基因a控制,那么黑色小狗的基因组成为 。
New York is one of the most exciting cities in the world.
You might want to do some shopping in New York. Fifth Avenue is probably New York’s most famous shopping street, but if you go, be prepared to "window shop" only. This is shopping for the rich. There are other, less expensive shopping areas nearby, and you’ll soon find famous stores such as Bloomingdale’s, Macy’s and FAO Schwartz. And if you’ve brought your rollerblades(滑板), then a visit to Central Park is a must. This is a large, open park right in the middle of Manhattan, but if you thought that people came here to relax, then you’d be wrong. Nobody sits in Central Park: they run, jog(慢跑), and most of all they rollerblade.
When you leave New York, you might be tired, but the one thing you won’t be is bored!
Where is for the rich to go shopping