单项选择题为确保温室内不被遮荫，前后排温室的间距一般应不少于( )。A. 温室顶高的2倍 B. “温室+棉被卷”高度的2倍C. 温室顶高的3倍D. “温室+棉被卷”高度的3倍
单项选择题Which of the followingis appropriate in addressing people? A、Professor Li B、Manager Zhang C、Accountant Liu D、Engineer Wang
