This summer, several provinces in the south of China was struck by floods, from ______ effects

the people are still suffering. [ ]

A. what

B. which

C. whose

D. that

冬天，菜农在蔬菜大棚里种植了黄瓜、番茄等蔬菜．请分析回答：

（1）在天气晴朗、温度适宜、肥料和水分充足的条件下，为提高蔬菜的产量，常采取的简易措施是______．

（2）夜间适当降低大棚内的温度，可以提高产量，这是因为温度较低时蔬菜______减弱，减少了有机物的消耗．

（3）在大棚内壁上会观察到有大量的水珠，这些水珠来源于______和______．