肺泡上皮由（）细胞和（）细胞构成，前者的功能是（）；后者主要分泌（）。
参考答案：Ⅰ型肺泡；Ⅱ型肺泡；气体交换；表面活性物质
What the remote areas need______ education to children and what the children need______ good textbooks at the moment .
A．is ; are
B．are; is
C．have; has
D．has; have
