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Xiǎo Míng: Nǐ zhè ɡe xīnɡ qī qù zhōnɡ ɡuó hái shì xià ɡè xīnɡ qī qù ？
小      明:    你  这  个   星  期  去   中      国   还  是  下  个   星   期 去？

Xiǎo Hóng: Xià ɡè xīnɡ qī.
小       红:    下  个   星   期。

Xiǎo Míng: Zěn me qù ？
小       明:    怎  么  去？

Xiǎo Hóng: Zuò huǒ chē huò zhě zuò fēi jī.
小      红:     坐    火    车   或   者    坐  飞 机。

1. 还是（hái shì）is normally utilized in two eventualities：

When the speaker makes use of it, it signifies she or he doesn’t know “which one or what scenario it’s”. It’s typically utilized in questions.

Eg:
nǐ xǐ huān píng guǒ hái shì cǎo méi？
你喜欢苹果还是草莓？
Which one do you want, apple or strawberry？

Generally it doesn’t have to seem in a query. That is when phrase like “bù zhī dào不知道: don’t know but，bù qīng chǔ不清楚: not clear，méi jué ding没决定: haven’t determined but，bú què ding不确定: undecided” is within the sentence, too.

Eg：
qù měi guó hái shì qù yīng guó，wǒ hái méi què dìng.
去美国还是去英国，我还没确定。
I’m undecided the place to go to, U.S. or U.Okay.

2. 或者(huò zhě): It’s usually not utilized in questions. The speaker makes use of it to inform others there are a number of potentialities.

Eg：
nǐ míng tiān lái huò zhě hòu tiān lái dōu kě yǐ.
你明天来或者后天来都可以。
You possibly can come tomorrow or the day after tomorrow.