◇ Semi-modal Verbs－Ought to
半情態動詞 ought to
ought to 意思為「應該」，它是一個半情態動詞，也就是具有情態動詞的特性，但後面卻總是跟著 to ，這點和其他情態動詞不一樣。情態動詞像是 should, must, could 等等，後面會加上原形動詞， ought to 也有這個特性，例句 Ethically, courage ought to be directed toward pursuits that are in favor of the common good. 可以看到後面接著原形動詞 be。ought to 不能當作句子的主要動詞，它的否定寫法為 ought not to。另外它和 should 一樣都有「應該」的意思，不同之處在於 ought to 比較正式。
Example：
1. Underwater oil drilling ought to have contingency plans in case of a massive oil spill.
水下石油鑽井應該有應急計劃，以防發生大規模漏油。
2. Reporters ought to uphold their journalistic integrity when covering the news.
報導新聞時，記者應該要秉持其新聞誠信。
3. We ought not to fly abroad because the pandemic is far from over.
我們不應該出國，因為疫情絲毫沒有停歇。