您先请用英语怎么说

In English, you would say "Excuse me, could you please speak in English?" or "Can you please speak in English?" The phrase "Excuse me" is a polite way of getting someone's attention, and "Could you please speak in English?" is a polite way of asking someone to speak in English. This phrase is commonly used when speaking to someone who is not a native English speaker, or when you are in a situation where English is the expected or desired language of communication.

Here are some examples of the phrase in use:

Excuse me, could you please speak in English? I don't understand what you're saying.

Can you please speak in English? I don't speak your language.

Excuse me, could you please speak in English? This is an English-speaking event.

In Chinese, this phrase would be: "不好意思，能请您用英语说吗？" (bù hǎo yìsi, néng qǐng nín yòng yīngyǔ shuō ma?)