| 2021 34 | | | 2021 | | | | 2021 7 21 | | 2021 | | | | ︹ 2021 ︺ 684 | | | | | | | | | | | | | | | | | | | 1. 2021 | | | | | | | 2 | | | | | 3 | | | | | | | | | ＝ | ÷2021 | 2021 | | | | | | | | 7 | | | 2021 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |