…得… / …不…【de / bù】

A potential complement says whether a result can be reached. Put 得 between a verb and its result complement for "can", and 不 for "can't". In both, the middle syllable is toneless.

Any result or direction complement can go into the frame: 听懂 "understood" becomes 听得懂 "can understand" and 听不懂 "can't understand"; 拿出来 "take out" becomes 拿不出来 "can't get out".

不能 or V不C

不能 says something is not allowed or not possible in the circumstances. V不C says you try and the result doesn't come. With understanding, seeing, hearing, finishing and finding, the result is what fails, so V不C is the form.

• × 我不能听懂 → 我听不懂
• × 我不能找到我的手机 → 我找不到我的手机

Questions

Add 吗, or put the positive and negative forms side by side.

Where the object goes

The object follows the whole complement, or moves to the front as the topic. It never goes between the verb and 得 / 不.

• × 我买火车票不到 → 我买不到火车票

A potential complement doesn't go in a 把 sentence: 这本书我看不懂, not 我把这本书看不懂.