a question about the compound sentence...

问题描述:

a question about the compound sentence...
on his way up the hill jack fell down and hurt his hands and knees,but jimmy got to the hill all right.这个句子是属于one sentence 还是two sentences?如何划分一个句子.有个逗号不是两句吗?如果逗号换成分号呢?

这是由but连接的表示转折的并列句,属于one sentence.英语中一个句号就是一句,有分号仍然算作一句.