Mistrustful describes a person — or a look, a mood, a whole public — that does not trust. You are mistrustful of someone when you think they may treat you unfairly or lie, so you keep your guard up.

Mistrustful describes用來形容 that does not trust不信任(人)的 a person一個人、or或 a look眼神、a mood情緒、a whole public整個大眾。when you think they may treat you unfairly or lie當你覺得對方可能會不公平對待你或說謊時，you are mistrustful of someone你就是對他抱持不信任，so you keep your guard up於是會提高警覺。

The meaning you are learning is that feeling of not trusting; the word itself is an adjective, not the verb. The verb is mistrust: “She mistrusts him.” The adjective is mistrustful: “She is mistrustful of him.” It is a little more formal than “I don’t trust them,” and it often suggests a habit or a standing attitude, not one bad afternoon.

The meaning you are learning你現在在學的意思 is that feeling of not trusting是那種不信任的感覺；the word itself這個字本身 is an adjective是形容詞，not the verb不是動詞。The verb動詞 is mistrust是 mistrust：“She mistrusts him.”她不信任他。The adjective形容詞 is mistrustful是 mistrustful：“She is mistrustful of him.”她對他心存不信任。than比 “I don't trust them,”『我不相信他們』 it is a little more formal這說法正式一點，and而且 it often suggests常帶有 a habit or a standing attitude一種習慣或長期的態度，not one bad afternoon而不是一時的心情不好。

Though actually, being careful is not the same as being mistrustful. Mistrustful already leans toward suspicion.

Though actually不過其實，being careful小心 is not the same as跟 being mistrustful不信任不一樣，因為 Mistrustful already已經 leans toward suspicion偏向懷疑了。