常常将处于幼年阶段的乔木层个体统称为（）
A.乔木层
B.草本层
C.更新层
D.活地被植层
参考答案：C
用所给词的适当形式填空。
1. She was _______ (bad) hurt when she fell off the tree.
2. I hope you will _______ (cover) soon.
3. He has been one of Dr. Clarks' _______ (patient) for many years.
4. The teacher walked into the class so _______ (quiet) that no one noticed him.
5. Comrade Lei Feng has been ______ (die) for many years.
不用于防龋的蔗糖代用品是（）
A.山梨醇
B.木糖醇
C.甜菊糖
D.果糖
E.甘露醇
