Premis
n. 前題
??? 情景例句
Hi, big guy.
嗨， 好小子。
If it doesn't rain tomorrow, I think I'll run some errands.
如果明天不下雨的話，你會打電話給我嗎？
For one thing they keep the water clean.
一來，水下植物可以保持水的清潔。