大黄根茎髓部呈星点状的异常维管束为（）
A.外韧型
B.周木型
C.双韧型
D.周韧型
E.环型
参考答案：B
.
In the market near our school, there are ______ supplies of fruits, fish and meat. You can buy whatever you like.
A．abundant
B．expensive
C．cheap
D．colorful
轴流风机进排气方式是（）
A.径向进气，逆流阀关
B.径向进气，轴向排气
C.轴向进气，轴向排气
