"These fish are very expensive."

Translation: 这些鱼非常贵。

[LaBiciEsMia]

And why not "这些鱼很贵“ ？

Why must we use 非常 in this example, instead of 很 ？

[DeiXu]

These are synonymous! "这些鱼很贵" should be accepted.

[CallMeDPP]

Both are acceptable ways to say it in Chinese. We don't actually must use it, it's just Duolingo makes mistakes.

[RembrandtQ1]

非常 is just a variation of 很, but 非常 is implies something nore extreme. How I put it into words is like saying "the fish is freaky expensive."

[ChaosScroll]

Zhexie = these

[Andrew-Lin]

這些魚非常貴。

[richard711603]

Is 这些鱼太贵 also a valid way of saying it?

[neil_05]

太 implies that it's too expensive. 这些鱼太贵 = These fish are too expensive.

[Zeejai]

Here you are saying that these fish are too expensive

[janetgusta]

Why is there no actual use of a verb in this sentence?

[captlu1]

In Chinese, adjectives can describe the subject without the need of a verb.
"很" is often used to link the subject and the adjective. If there are adverbs like "非常", "太", then "很" is not required

[ph.nfskam.438]

这玩意儿太难了！