某粒子的结构示意图为
．下列说法不正确的是（ ）
A．该粒子质子数为l2
B．该粒子是一种原子
C．该粒子具有稳定结构
D．该粒子有3个电子层
A、根据微粒结构示意图的含义，可知该粒子质子数为l2；故A说法正确；
B、由微粒结构示意图可知核电荷数=质子数=核外电子数=12，为原子；故B说法正确；
C、根据通常认为最外层有8个电子（最外层是第一电子层时有2个电子）的结构是一种稳定结构，由微粒结构示意图可知最外层电子数为2，因此该粒子不具有稳定结构；故C说法错误；
D、根据微粒结构示意图，可知该粒子有3个电子层；故D说法正确；
故选D．
| Some people associate migration mainly with birds. Birds do travel vast distances, but mammals also migrate. An example is the caribou, reindeer that graze on the grassy slopes of northern Canada. When the weather turns cold, they travel south until spring. Their tracks are so well-worn that they are clearly visible from the air. Another migrating mammal is the Alaska fur seal. These seals breed only in the Pribilot Islands in the Bering Sea. The young are born in June and by September are p enough to go with their mothers on a journey of over 3,000 miles. Together they swim down the Pacific Coast of North America. The females and young travel as far as southern California. The males do not journey so far. They swim only to the Gulf of Alaska. In the spring, males and females all return to the islands, and there the cycle begins again. Whales are among the greatest migrators of all. The humpback and blue whales migrate thousands of miles each year from the polar seas to the tropics. Whales eat huge quantities of plankton. These are most abundant in cold polar waters. In winter, the whales move to warm waters to breed and give birth to their young. |
Where can you see from the air the migration of the mammals
A．In the Pribilot Islands.
B．In the Bering Sea.
C．In southern California.
D．In northern Canada.