太阳、地球、月亮、平面镜，其中属于光源的是______．光在真空中的传播速度是_

阅读下面短文，然后根据括号内所给汉语意思写出单词的正确形式（每空一词）。

At   小题1:  ( 目前 ), teenagers want to be independent ( 独立的) from their parents as   小题2:  ( 快地 ) as possible. Many parents are   小题3:  ( 焦虑的 ) about it . Most teenagers are the only child in their family. They are always  小题4:（视为）as the little kids by their parents. But I think teenagers should be allowed to be independent because they have to   小题5: ( 面对 ) the challenges and difficulties in the future by   小题6:( 他们). So learning to be independent   小题7: ( 似乎) very important. 小题8: （无论什么）they do, I think teenagers should learn to do it on their own.It’s a really exciting experience. Teenagers shouldn't be  小题9: (害怕的) of learning to be independent,   小题10: (虽然）there will be some trouble. Nothing is impossible and they will take pride in themselves in the future.

在重大疫情引起粮食市场供求异常波动时，可考虑实施粮食应急机制。（）

（）又名《结水浒传》，是（）晚年作品。

中国古代园林的发展在（）时期发生较大转折，转向崇尚自然

A、春秋战国

B、秦汉

C、魏晋南北朝

D、唐宋

主龙骨架的调平是以（）为单位进行调平调直。

A.一根主龙骨

B.一个操作面

C.一个施工段

D.一个房间