蓝藻、酵母菌、变形虫的细胞都有的结构是[ ]
A．叶绿体
B．线粒体
C．核糖体
D．细胞核
答案：C
I have reached a point in my life ______ I am supposed to make decisions of my own. [ ]
A. which
B. where
C. how
D. why
图根三角的基线丈量，按（）级导线技术要求实施。
A.三级
B.四级
C.图根
D.二级
