最有利于植物生长的土壤结构是（）。
A.团粒结构
B.片状结构
C.块状结构
D.柱状结构
参考答案：A
To reduce air pollution, a large number of people in London go to work by bike or on foot, _____
do many of my friends in China.[ ]
A. as
B. which
C. while
D. where
汽轮机跟随锅炉控制方式的基本原理是什么？
