短日照作物要求在24小时昼夜周期中,日照长度（）于某个临界日照长度,才能正常开花结实。
参考答案：短
用所给词的适当形式填空。
1. My uncle often ____________ (watch) TV after supper.
2. Tom lives on the ____________ (five) floor.
3. She likes ____________ (sing) and dancing.
4. She ____________ (go) to work by bus every morning.
5. A salesperson can ____________ (be) either a man or a woman.
下面不属于钢结构深化设计的目的的是（）。
A、材料优化
B、构造优化
C、确保安全
D、复核构件强度
