表面紫红色或红褐色,有致密的纹理,质硬,有油性的是()
A.大血藤
B.沉香饮片
C.降香饮片
D.苏木饮片
E.通草饮片
参考答案:C
_______ is important for us to learn English well.
A.What
B.That
C.It
D.Which
什么是水体的有毒物质污染?