西安电子科技大学历年专升本分数线是多少呢？

“一国经济的立身之本。财富创造的根本源泉，国家强盛的重要支柱”指的是（ ）

A.实体经济
B.虚拟经济
C.教育
D.科技创新

合成甲状腺素的主要原料有（　　）

A.碘和酪氨酸

B.碘和亚铁

C.铁和酪氨酸

D.球蛋白和类固醇

E.甲状腺球蛋白

The dog has always been considered man′s best friend.Always noted for being particularly?faithful in watching over children,he also has his place by the fireside,in the cow pasture,on the?sheep range(放牧区),and beside the hunter in forest.He is easy to train,works hard,and often?performs astonishing feats.And in the frozen polar regions he was once the principal motive power,before being lately displaced by the plane and helicopter.
Because he howls or whines in the presence of impending death,the dog was once thought to?have supernatural powers and believed to be capable of seeing gods and ghosts invisible to men.Actually,the.basis for these beliefs lies in the hound′s sensibility to people′s feelings and his superior?hearing ability and sense of smell,which enable him to detect signs hidden from human observation.His record of saving lives is outstanding,for he often gives warning of fire and other dangers not noticed by his master.
The dog′s major contribution,however,has been to medical research.Both his diet and his?structure are comparable to those of the human being,and so he has been the subject Of countless?demonstrations and experiments.Open-heart surgery has been made possible largely because of the?dog.But his sacrifice has repaid his own species as well by safeguarding it from rabies(狂犬病),distemper,and other diseases.

In the polar regions,the dog mainly__________.

A.carried supplies
B.provided companionship
C.tracked prey
D.herded caribou（驯鹿）