The teacher conducted a single lesson on the topic of photosynthesis to cover the basic concepts.
老师进行了一堂关于光合作用的单一课，以涵盖基本概念。
Due to the short notice, the instructor had to prepare a single lesson for the emergency meeting.
由于通知时间紧迫，讲师不得不为紧急会议准备一堂单一课。