English Grammer

From my point of view, they are both grammatically correct. However, I think the second sentence is better.

They乃人稱代名詞 , 應用: which/ those are beautiful.

1/ I have collected twenty shells, they are beautiful.
You have a run-on sentence. The above sentence is grammatically wrong.

2/ I have collected twenty shells. They are beautiful. ~ correct
The second sentence is correct.

Alternatively, you can use a semi-colon (;) instead of a full stop, in case where sentences are grammatically independent but the meaning is closely related.

I have collected twenty shells;they are beautiful.



2011-06-14 23:43:48 補充：
THEY can refer to people and things.
e.g. "How much are these eggs?" "They are $2.50 a dozen."

Quoted from:
Oxford Advanced Learner’s Dictionary,
 
1 people, animals or things that have already been mentioned or are easily identified

They (= the things you are carrying) go on the bottom shelf.

i think that:

I have collected twenty shells which are beautiful .


th second sentence is right,but not good.. use (,) before (they are beautiful)

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我自己都去開, 希望可以幫到你~ ^T^
比我20分!