16. 世上没有什么比…更令我高兴。
Nothing in the world can delight me so much as …
例┱世上没有什么比到快餐店吃汉堡更令我高兴。
Nothing in the world can delight me so much as having hamburgers in fast-food restaurants.
17. … 是必要的 It is necessary that S (should) V
… 是重要的 It is important/essential that S (should) V
… 是适当的 It is proper that S (should) V
… 是紧急的 It is urgent that S (should) V
例┱我们当保持公共场所清洁是应当的。
It is proper that we (should) keep the public places clean.
18. 每当我听到…我就忍不住感到兴奋。Whenever I hear …， I cannot but feel excited.
每当我做…我就忍不住感到悲伤。 Whenever I do …， I cannot but feel sad.
每当我想到…我就忍不住感到紧张。Whenever I think of …， I cannot but feel nervous.
每当我遭遇…我就忍不住感到害怕。Whenever I meet with …， I cannot but feel frightened.
每当我看到… 我就忍不住感到惊讶。Whenever I see …， I cannot but feel surprised.
例┱每当我想到我家附近那一条清澈的小溪我就忍不住感到悲伤。
Whenever I think of the clean brook near my home， I cannot but feel sad.
= Every time I think of the clean brook near my home， I cannot help feeling sad.