1. What a pity!

2. What a shame!
3. What a suck!
4. That sucks!
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Are they all grammatical? Are they the same? Which ones are commonly used? What is the meaning of 'suck' in the sentences?

The first two sentences are right.

In those two sentences, the word "suck" is slang and is not used in polite conversation.

1. "What a pity!" - This sentence is grammatically correct and is commonly used. It expresses regret or sadness about a situation or outcome.

2. "What a shame!" - This sentence is also grammatically correct and commonly used. It conveys disappointment or disapproval about something that has happened or a missed opportunity.

3. "What a suck!" - This sentence is grammatically incorrect and does not make sense. It seems to be a misinterpretation or misuse of language.

4. "That sucks!" - This sentence is grammatically correct and commonly used. It expresses dissatisfaction or disappointment with a situation or something that has happened. It is an informal way of saying that something is unpleasant or unfortunate.

The word "suck" in these sentences is an informal slang term that means something is bad, unfortunate, or disappointing. It is often used to express frustration or disappointment with a particular situation or outcome. However, it should be noted that this word is considered less formal and may not be appropriate in all contexts.