The conjunctions 不然 and 要不然
The conjunctions 不然 
and 要不然 have the same meaning "otherwise”, “or" and indicate that if a certain condition is not met, there will be undesirable consequences.
In a sentence, the condition is usually described before 不然 and 要不然. Possible negative consequences that can happen if a certain condition is not met are described after 不然 and 要不然.
and 要不然 have the same meaning "otherwise”, “or" and indicate that if a certain condition is not met, there will be undesirable consequences.
In a sentence, the condition is usually described before 不然 and 要不然. Possible negative consequences that can happen if a certain condition is not met are described after 不然 and 要不然.Scheme
condition
(要)不然
undesirable consequences
Examples
帮助他，不然他会死的
Help him or he will die
bāngzhù tā, bùrán tā huì sǐ de
大家要认真对待考试，要不然会影响毕业的
Everyone should take the exam seriously. It can affect how the end of the course is taught
dàjiā yào rènzhēn duìdài kǎoshì, yàoburán huì yǐngxiǎng bìyè de
快点吧，要不然你今天准会迟到
Hurry up or you'll be late today
kuài diǎn ba, yàoburán nǐ jīntiān zhǔn huì chídào