木支架的梯形结构，一般棚梁与棚腿之间的夹角保持（）度为好。
参考答案：100~105
变性珠蛋白小体生成试验阴性，参考值是含5个以上珠蛋白小体的红细胞不超过（）
A.60%
B.40%
C.30%
D.20%
E.10%
—Excuse me .I want to buy some stamps. Where can I find a post office?
----I know _______not far from here. You can easily find ________.
A. that; it B. it; one C. one; it
