General expressions:
* 确定 (què dìng) - This is the most common and direct translation of "to be sure". It means "to confirm" or "to be certain".
* 保证 (bǎo zhèng) - This translates to "to guarantee" or "to ensure", implying a higher level of confidence.
* 肯定 (kěn dìng) - This means "to affirm" or "to be sure without a doubt".
* 一定 (yī dìng) - This translates to "definitely" or "certainly".
More nuanced expressions:
* 一定得 (yī dìng de) - This phrase implies a strong obligation or necessity, and translates to "must be sure".
* 务必 (wù bì) - This means "must" or "absolutely", emphasizing the importance of being sure.
* 万无一失 (wàn wú yī shī) - This idiom means "absolutely safe" or "without any room for error".
* 十拿九稳 (shí ná jiǔ wěn) - This idiom means "to have a 90% chance of success" and implies a very high level of confidence.
Example sentences:
* 你确定要这样做吗? (nǐ què dìng yào zhèyàng zuò ma?) - Are you sure you want to do this?
* 我保证会按时完成任务。 (wǒ bǎo zhèng huì àn shí wán chéng rèn wù.) - I guarantee I will finish the task on time.
* 这件事肯定是真的。 (zhè jiàn shì qíng kěn dìng shì zhēn de.) - This matter is definitely true.
* 你一定要来参加我的生日派对！ (nǐ yī dìng yào lái cān jiā wǒ de shēng rì pàidui!) - You must come to my birthday party!
* 务必确保所有设备都安全。 (wù bì què bǎo suǒ yǒu shè bèi dōu ān quán.) - Be absolutely sure all equipment is safe.
The best way to choose the right phrase depends on the specific situation and the level of certainty you want to express.