物料平衡的计算基础是()。
参考答案:物质不灭定律
About half of million of Afghans have no_______ to basic health services due to continued war and
conflicts.[ ]
A. means
B. approach
C. channel
D. access
风疹的流行季节是:()
A.夏秋
B.冬春
C.秋冬
D.春夏
E.春秋