She suddenly changed her personality, surprising everyone.

He hit a jackpot at the pachinko.

Linear programming is a part of operations research and is used to find the optimal solution.

She is learning how to use prepositions in Chinese.

In Chinese grammar, separable verbs play a very important role.

His speech skillfully used interjections, captivating the audience.

It's difficult to make sentences using interrogatives.

It's difficult to make sentences using infinitives.

The interjection 'Ah!' expresses his surprise.

He expresses numbers using numerals.