The Chinese character 想 (xiǎng) can mean three different things depending on how it is used. Since it is a pretty commonly used character, let’s look at its three uses:
(i) 想 + Somebody/Something
我想你 (Wǒ xiǎng nǐ): I miss you
When used in this form, 想 means to miss somebody/something.
If someone says that to you and you feel the same way too, then you can respond
我也想你(Wǒ yě xiǎng nǐ): I miss you too
想家(Xiǎng jiā): homesick
(ii) 想 + Verb Phrase
我想去中国(Wǒ xiǎng qù Zhōngguó): I want to go to China
In the above structure, 想 means the desire to do something.
(iii) 想 + Clause
我想他是中国人(Wǒ xiǎng tā shì Zhōngguórén): I think he is Chinese
Here 想 is used to express someone’s opinion.
But how to ask someone what he or she is thinking
你在想什么？(Nǐ zài xiǎng shénme?): What are you thinking?