Here are five simple expressions to say "I don't understand" in Chinese, * 我不知道。 (wǒ bú zhī dào.) (I don't know.) * 我不明白。 (wǒ bú míng bai.) (I don't understand.) * 我搞不清楚。 (wǒ gǎo bù qīng chǔ.) (I don't understand.) * 我不会。 (wǒ bú huì.) (I don't know how.) * 我不懂。 (wǒ bú dǒng.) (I don't understand.) Here are examples of them used in a sentence: 1. 我不知道 (wǒ bú zhī dào) - I don't know Example: 我不知道你在说什么。 (wǒ bú zhī dào nǐ zài shuō shén me.) (I don't know what you're saying.)
 2. 我不明白 (wǒ bù míng bai) - I don't understand Example: 我不明白这道题怎么做。 (wǒ bù míng bai zhè dào tí zěn me zuò.) (I don't understand how to do this problem.)
 3. 我搞不清楚 (wǒ gǎo bù qīng chǔ) - I don't understandExample: 我搞不清楚这个词的意思。 (wǒ gǎo bù qīng chǔ zhè gè cí de yì si.) (I don't understand the meaning of this word.)
 4. 我不会 (wǒ bú huì) - I don't know how Example: 我不会用这个软件。 (wǒ bú huì yòng zhè gè ruǎn jiàn.) (I don't know how to use this software.)
 5. 我不懂 (wǒ bú dǒng) - I don't understand Example: 我不懂你在讲什么。 (wǒ bú dǒng nǐ zài jiǎng shén me.) (I don't understand what you're talking about.)