下列区域属于自然区域的是( )
A.阿坝藏族自治州
B.黄土高原
C.长岛海水养殖区
D.烟台经济开发区
属于自然区域的是黄土高原.选项ACD均不是自然区域.根据题意.
故选:B.
She felt completely during the vacation but now she has to go back to her work again.
A.at sea
B.at ease
C.at a loss
D.at risk
先天性心脏病出现下半身青紫时应考虑为()。
A.房间隔缺损
B.室间隔缺损
C.动脉导管未闭
D.法洛四联症
E.二尖瓣狭窄