Notuntiltheirhealthisthreatened,willthedietersbecautiousofthebadeffectsofextremediet.中的willthedietersbecautiousof是什么语法啊,为什么有个be动词啊,还是becautiousof是固定搭配,还是will提前了,be动词

Question

Not until their health is threatened,will the dieters be cautious of the bad effects of extreme diet.中的will the dieters be cautious of 是什么语法啊,为什么有个be动词啊,还是be cautious of 是固定搭配,还是will提前了,be动词还原啊,请英语达人赐教,

Answer 1

这是个否定倒装句,把until提前,否定词放在句首.
试着还原一下：The dieters will not be cautions of the bad effects of extreme diet until their health is threatened.
be+形容词+of 的用法很常见,在句中的作用等于动词.
如：
be afraid of 害怕
be ashamed of 为……感到羞愧
be aware of 意识到,知道
等等.