A:150°
B:80°
C:50°或80°
D:70°
Bryant is my uncle. I know a lot ____(关于) him. He has a ____(儿子). He reads a lot in the city ____(图书馆). My uncle can ____(拼写) many English words. He is very ____(井井有条的). He ____(总是) puts his books in the bookshelf. I ____(必须) learn from him.He also likes animals. He has____(一些)pet ducks and two pet dogs. One dog is called ____(零) and the other is called One. My uncle is ____(他们的) good friend.
按照题目要求作图:
(1)如图甲所示是光纤传输的原理图,画出光信号从一端传播到另一端的路径图.
(2)根据图乙中给出的已知条件,画出螺线管的绕法.
(3)小明想自己制作一个楼梯门铃,准备的器材有:电池组、一个电铃、一个电动机、开关导线若干.要求:当楼下有人按开关时时,楼上的门铃响,他可以通过室内的开关来控制开门的电动机、请你在图丙方框内画出小明设计的电路图.
如图显示的是两类生物细胞分裂过程,据图回答下列问题。
“穿花蛱蝶深深见,点水蜻蜓款款飞”,这句诗里分别描述了蛱蝶、蜻蜓的
亚马孙河是世界上最长的河流。