The four tones of Chinese language increase the difficulty of pronunciation.

The Holocene, in geology, is the most recent geological epoch, lasting from about 10,000 years ago to the present.

He is suffering from acquired immunodeficiency syndrome.

Calculating the value of secant, one of the trigonometric functions, is difficult.

I, in my humble capacity, respect your opinion.

He is accustomed to life on the street.

He is studying the traditional Baijiaxing (Hundred Family Surnames) of China.

He was born as an illegitimate child and experienced many difficulties.

I am planning to go to Seiyo, a city in Ehime Prefecture, next week.

He started studying the day before the exam, which was exactly a case of failing to make a timed preparation.