副淀粉
参考答案：
副淀粉是植物经光合作用制造的营养物质的同化产物。是一光亮带白色而不透明的物体，但是它多半是比较大形而且是环状中空或棒状或椭圆形或或球形。
Not until one of his works was published_________to gain his confidence in writing. [ ]
A. he was able
B. was he able
C. he had been able
D. had he been able
下列关于配制混凝土砂率选择的描述，不合理的是（）。
A.砂的细度模数较小时，则应选择较小的砂率
B.水灰比较小时，则应选择较小的砂率
C.配制混凝土时，应选择合理砂率
D.流动性较大时，则应选择较小的砂率
