通读下面短文，掌握其大意，然后在各小题所给的四个选项中，选出一个最佳答案。
Every April, there is a special day when people remember and honor their ancestors (祖先). It is called Tomb (坟墓)-Sweeping Day, also known as Qingming Festival. This year, the day 1 on April 4th.
Tomb-Sweeping Day is a(n)2 Chinese festival. It began over 2,000 years ago. A well-known poem by the Tang Dynasty poet Du Mu 3 the day: “Rains fall heavily as Qingming comes, and passersby with lowered spirits go. A drizzling rain falls on the mourning Day, the mourner's heart is breaking on his way.”
Tomb-Sweeping Day has been a public 4 on the Chinese mainland since 2008. On this day,5 bring flowers, food and wine to their ancestors' tombs (坟墓). They put food like cakes and fruits in front of the tombs. After that, they 6 the dirt (尘土) off the tombs and remember their dead family members.
7 do Chinese people do this? That's because people think that visiting tombs during Qingming Festival is to 8 respect (尊重) to their dead family members.
However, Tomb-Sweeping Day is not only about this. During that time, the weather is getting 9. So Tomb-Sweeping Day also means finally being able to garden and enjoy outdoor activities in China. Families often 10 for outings or fly kites at this time.
2SO3 的反应，己知反应过程中某一时刻的数据是： SO2、O2、SO3的浓度分别是0.2mol/L、0.1mol/L、 0.2mol/L，当达平衡时可能数据是