1) Do we say "The information is correct as of 28 September 2010." or "The information is correct as at 28 September 2010."?

2) "I spoke with him yesterday." or "I spoke to him yesterday."? Someone mentioned to me that both sentences are acceptable but 1 of them is more formal. Which is it?

Thanks.

1. "as of"

2. Both are correct. I don't see that one is more formal than the other.

2. I would say I spoke with him yesterday is more formal.

I think the difference in number 2 is whether you spoke to him with little or no response from him or whether it was a mutual conversation -- with him.

1) Both options, "as of" and "as at," are grammatically correct and convey the same meaning. However, the usage may vary based on regional preferences or personal style. In general, "as of" is more commonly used in American English, while "as at" is more commonly used in British English. Nevertheless, there is no significant difference in meaning between the two phrases.

To decide which phrase to use, consider the language conventions in your specific context. If you are writing for an audience primarily in the United States, using "as of" may be more appropriate. If you are writing for an audience primarily in the United Kingdom or other Commonwealth countries, using "as at" may be more suitable. Ultimately, the choice of phrase is a matter of personal preference and maintaining consistency within your writing.

2) Both sentences, "I spoke with him yesterday" and "I spoke to him yesterday," are grammatically correct and express the same basic idea. However, there may be a slight difference in formality between the two options.

"I spoke with him yesterday" is more commonly used in American English and is considered slightly less formal. It implies a two-way conversation or a discussion between both parties involved.

On the other hand, "I spoke to him yesterday" is more commonly used in British English and is considered slightly more formal. It implies a one-way communication, where one person is speaking or delivering a message to another person.

However, it's important to note that the distinction between the two options is relatively subtle and may not be strictly adhered to in all situations. In most cases, both sentences are interchangeable, and the choice between "with" and "to" can be a personal preference or a matter of regional variation.

When deciding which sentence to use, it's advisable to consider the writing style or the context in which you are communicating. If you are writing informally or in a casual setting, either option can be used. If you are writing more formally or in a professional setting, "I spoke to him yesterday" may be more appropriate.