It was not very pleasant.

这不是很愉快。

I was not born in Beijing.

我不是出生在北京。

It was not a happy time.

这不是一个愉快的时光。

It was not a small village then.

那时不是一个小村庄。

The accident was not the driver's fault.

这次事故不是司机的错。

The attack was not spontaneous; it was premeditated.

这次袭击不是自发的，而是预谋的。

The lawyer argued that his client was not extraditable.

律师辩称他的客户不是可引渡的。

His austere expression made it clear he was not joking.

他严厉的表情表明他不是在开玩笑。

Their trip was not plain sailing.

他们的旅行并不是一帆风顺的。

In retrospect, the decision was not the best one.

回顾起来，这个决定并不是最好的。