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题库 / Prep2008E1-SC-246
Scientists have identified an asteroid, 2000 BF19, that is about half a mile wide and, if it strikes Earth, it can do tremendous damage to part of the planet but probably not cause planetwide destruction.
and, if it strikes Earth, it can do tremendous damage to part of the planet but
and, if it would strike Earth, part of the planet could experience a tremendous amount of damage but it would
and that, if it were to strike Earth, could do tremendous damage to part of the planet but would
and that, if Earth is struck by it, can do part of the planet tremendous damage, but it would
and that, if it strikes Earth, it could experience a tremendous amount of damage but
题目分析：
本题涉及许多虚拟语气的相关概念。
选项分析：
A选项：由于并列连词and身后没有that，且 it can do tremendous damage to part of the planet是完整的不缺少任何成分的完整句（定语从句中必然缺少某个成分），所以本选项中具有并列关系的是Scientists have identified an asteroid, 2000 BF19和 it can do tremendous damage to part of the planet。在逻辑上，前者是表述发现行星的，后者是描述行星特点的，两者没有并列关系。
B选项：本选项错误同选项(A)。另外，虚拟语气中的if从句不能用would。
C选项：Correct. 本选项在语法和逻辑上均是正确的。
D选项：并列连词but身后的it would probably not cause planetwide destruction中是完整的句子，无法和定语从句并列，只能和主句Scientists have identified an asteroid, 2000 BF19并列。同(A)理，这种并列是不成立的。
E选项：并列连词and身后的it can do tremendous damage to part of the planet是完整的不缺少任何成分的完整句，并列关系错误同选项(A)。另外，if从句用一般现在时，主句需用将来时，不能用could。
D：不平行。
E：错误使用一般现在时，一般现在时用来描述一个不变的现象。
if did, then would do/could do
if had done, then would have done/could have done
if did, then would do/could do
if had done, then would have done/could have done
in this sentence, those two ideas are the two facts about the asteroid:
* the asteroid is about 1/2 mile wide.
* if the asteroid strikes earth, blah blah blah xxxxx will happen.
选项A的情况and也可以实现并列。比如：I found a garden, and it is beautiful. and表示顺承上句，进一步解释。
请老师指正。
解释已经写的非常清楚了。and是并列连词，连接两者必须在逻辑上对等。你给出的这个例句，应该改成：I found a beautiful garden.
或者换成非限制性定语从句也许也可以。
你说的是对的， 别听那老师瞎说，A就是and前少了个逗号所以不对登录 或 注册 后可以参加讨论