你不必担心这个问题。
nǐ bùbì dānxīn zhègè wèntí 。
You need not worry about this problem.
今天的会议你不必参加。
jīntiān de huìyì nǐ bùbì cānjiā 。
You do not have to attend today's meeting.
他已经解决了这个问题,你不必再说了。
tā yǐjīng jiějué le zhègè wèntí , nǐ bùbì zàishuō le 。
He has already solved the problem, you need not say anything more.