在科学写作中，下列哪个句子是正确的?

1. The mean score among the students was 20. The score among the staff was 10 however.

2. This study used a small sample. Our previous study however used a large sample.

3. This interview study reveals varied responses from 10 students, however small group data cannot be generalized.

4. The interview responses from the students however small the group reveal problems with the new policy.

这些句子都可以改进。首先，“however”可以是表示对比的副词，在句中位置较灵活。在句子（1）中，在最后一个词“however”之前添加一个逗号，有助于将对比表达清楚：“The score among the staff was 10, however”。当表示对比的“however”出现在句子中间时，比如句子（2），两边都加上逗号可以更清楚：“Our previous study, however, used a large sample.”与“In contrast,…”或“By contrast,…”类似，“however”也可以移到开头，后面跟一个逗号：“However, our previous study used a large sample.”

其次，“however”可以是让步副词（承认相反），如“nevertheless”、“still”、“at the same time”或“in spite of that”。在句子（3）中，有两个独立的子句，每个子句可以是一个完整的句子，因此在“however”之前需要一个完整的句号或分号。有些作者在“however”在句首时后面不加逗号，但加了逗号更清楚。在形容词“small-group”之间加一个连字符更好：“However, small-group data cannot be generalized.”

第三，“however”可以是程度副词，意思是no matter how，如句子（4）。它也表示让步，但在“however”和形容词“small”之间没有逗号。因为短语“however small the group”是额外的信息，应该放在一对逗号之间：“The interview responses from the students, however small the group, reveal problems with the new policy.”