需要做... 解释：It's something that we should do or it's important to us to do. （表明这件事情很重要或者我们应该去做） I/They/We/You need to She/He needs to I/They/We/You don't need to... She/He doesn't need to... I need to get my hair cut, it's out of control. 我要去剪头发了，我的头发已经不受控制了。 She needs to go to the dentist tomorrow. 她明天需要看牙医。 I need to make a phone call. 我需要打个电话。
have to/must
①相同点： ▶表达某事是一种义务，是一种必要的责任，或者某事是必要的。这件事不仅仅重要，还是必须的。解释：Something is an obligation, a necessity or a responsibility or something that is required. I have to/must get to my meeting on time. 我必须按时参加会议。 You have to/must have a passport to travel abroad. 你出国得有护照。 ▶表示可能性 解释：Something is likely. The heater must/has to be broken. 加热器可能坏了。 ②不同点must通常指个人义务；have to通常用于外部的权威或规定 I must turn off my phone when I study because it's too distracting. 我必须在学习时关掉手机，因为它太让人分心。 You have to turn off your phone during exams because it's a university rule. 你必须在考试期间关掉手机，因为这是大学规定。
