Sigma bond
[化] σ键
🧩 词语组成解析
[计] 求和\\n[医] σ(希腊文第十八个字母)
🗣️ 情景例句
I'm having some trouble keeping food down.
我吃东西时感到困难。
The law is not the same at morning and at night.
早上的法令跟晚上的不一样；朝令夕改。
There was no electricity in my dorm last night.
昨晚我宿舍没电。