first default options 首次违约期权
If an application is not performing adequately, it is generally more desirable to add more columns to an existing index, or add new indexes to a table as your first options.
如果一个应用程序执行时的性能不合格,较为可取的做法通常是添加更多的列到现有的索引中,或者为一个表添加新的索引,这种做法是首选。
Although e-bikes first appeared in the 90s, cheaper options and longer-lasting batteries are breathing new life into the concept.
虽然电动自行车最早出现在上世纪90年代,但更便宜的选择和更持久的电池正在给这一概念注入新的活力。
So what we're doing is filling in those eight electrons following the Aufbau principle, so our first electron is 1s going to go in the 1 s, and then we have no other options for other orbitals that are at that same energy, 1s so we put the second electron in the 1 s as well.
它会是什么样子呢,我们正在做的是将这8个电子按照奥弗,堡原理进行填充,所以我们第一个电子将会进入,然后我们没有其他的,轨道的选择在同一个能级,所以我们把第二个电子也放入。
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